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Digitized  by  the  Internet  Archive 
in  2013 


http://archive.org/details/essaysofbenjaminOOfran 


I         ESSAYS  OF 
BENJAMIN  FRANKLIN 


MORAL,  SOCIAL  and  SCIENTIFIC 


Compiled  by 

GEO.  HAVEN  PUTNAM 
LittJX 


G.  P.  PUTNAM'S  SONS 
New  York  —  London 
The  Knickerbocker  Press 
1927 


103215 


CONTENTS 


I. — To  Peter  Collinson        ....  3 

II. — Electrical  Experiments  ....  5 

III.  — To  John  Lining,  at  Charleston,  South 

Carolina   12 

IV.  — To  John  Pringle   21 

V. — To  John  Lining,  at  Charleston      .       .  22 

VI.— To  Oliver  Neave   28 

VII.— To  M.  Dubourg   33 

VIII.— To  M.  Dubourg       .       .       .       .  -37 

IX— To  M.  Dubourg   38 

X. — From  M.  Dubourg   42 

XL — To  M.  Dubourg   46 

XII. — To  Dr.  Brownrigg  .....  49 

XIII. — The  Ephemera:  An   Emblem  of  Human 

Life   63 

XIV— The  Whistle   66 

XV. — Aurora  Borealis     .....  70 

XVI.  — An  Economical  Project  ....  77 

XVII.  — To  Edward  Nairne,  of  London  .  .  84 
VIII. — To  John  Ingenhousz        ....  91 

iii 


Contents 

J 

XIX. — An  Account  of  Toads  Found  Enclosed  in 

Solid  Stone   11 

XX. — To  L'Abbe  Soulavie                              .  i 

XXI. — Propositions  Relative  to  Privateering 

Communicated  to  Mr.  Oswald     .       .  i 

j 

XXII. — To  Sir  Joseph  Banks      .                     .  t 

XXIII.  — Meteorological       Imaginations  and 

Conjectures  .       .       .       .       .       .  t 

XXIV.  — To  David  Rittenhouse  .  .  .  .  i 
XXV.— To  David  Le  Roy   I 

XXVI— To  James  Bowdoin   i 


iv 


ESSAYS  OF  BENJAMIN  FRANKLIN 

MORAL,  SOCIAL  AND  SCIENTIFIC 


I 


TO  PETER  COLLINSON 

Philadelphia,  18  April,  1754. 

Sir: — Since  September  last,  having  been  abroad 
on  two  long  journeys  and  otherwise  much  engaged,  I 
have  made  but  few  observations  on  the  positive  and 
negative  state  of  electricity  in  the  clouds.  But  Mr. 
Kinnersley  kept  his  rod  and  bells  in  good  order,  and 
has  made  many. 

Once  this  winter  the  bells  rang  a  long  time  during 
a  fall  of  snow,  though  no  thunder  was  heard  or  light- 
ning seen.  Sometimes  the  flashes  and  cracks  of  the 
electric  matter  between  bell  and  bell  were  so  large 
and  loud  as  to  be  heard  all  over  the  house ;  but  by 
all  his  observations  the  clouds  were  constantly  in  a 
negative  state,  till  about  six  weeks  ago,  when  he 
found  them  once  to  change  in  a  few  minutes  from 
the  negative  to  the  positive.  About  a  fortnight  after 
that  he  made  another  observation  of  the  same  kind, 
and  last  Monday  afternoon,  the  wind  blowing  hard 
at  southeast  and  veering  round  to  northeast,  with 
many  thick,  driving  clouds,  there  were  five  or  six 
successive  changes  from  negative  to  positive,  and 

3 


4 


Benjamin  Franklin 


[1754 


from  positive  to  negative,  the  bells  stopping  a  minute 
or  two  between  every  change.  Besides  the  methods 
mentioned  in  my  paper  of  September  last  of  discover- 
ing the  electrical  state  of  the  clouds,  the  following 
may  be  used.  When  your  bells  are  ringing,  pass  a 
rubbed  tube  by  the  edge  of  the  bell,  connected  with 
your  pointed  rod ;  if  the  cloud  is  then  in  a  negative 
state,  the  ringing  will  stop;  if  in  a  positive  state,  it 
will  continue,  and  perhaps  be  quicker.  Or  suspend 
a  very  small  cork  ball  by  a  fine  silk  thread,  so  that 
it  may  hang  close  to  the  edge  of  the  rod-bell;  then, 
whenever  the  bell  is  electrified,  whether  positively 
or  negatively,  the  little  ball  will  be  repelled  and  con- 
tinue at  some  distance  from  the  bell.  Have  ready 
a  round-headed  glass  stopper  of  a  decanter,  rub  it  on 
your  side  till  it  is  electrified,  then  present  it  to  the 
cork  ball.  If  the  electricity  in  the  ball  is  positive, 
it  will  be  repelled  from  the  glass  stopper,  as  well  as 
from  the  bell;  if  negative,  it  will  fly  to  the  stopper. 

B.  Franklin.1 

1  Soon  after  writing  this  letter  Franklin  set  out  on  a  tour  to  New 
England. 


II 


ELECTRICAL  EXPERIMENTS 

Made  in  Pursuance  of  those  made  by  Mr.  Canton,  dated 
December  6,  1753;  with  Explanations,  by  Benja- 
min Franklin 

READ  AT  THE  ROYAL  SOCIETY,  DECEMBER  1 8,  1 755 

Philadelphia,  14  March,  1755. 
PRINCIPLES 

I.  Electric  atmospheres  that  flow  round  non-elec- 
tric bodies,  being  brought  near  each  other,  do  not 
readily  mix  and  unite  into  one  atmosphere,  but  re- 
main separate  and  repel  each  other. 

This  is  plainly  seen  in  suspended  cork  balls  and 
other  bodies  electrified.  v 

II.  An  electric  atmosphere  not  only  repels  another 
electric  atmosphere,  but  will  also  repel  the  electric 
matter  contained  in  the  substance  of  a  body  ap- 
proaching it,  and,  without  joining  or  mixing  with  it, 
force  it  to  other  parts  of  the  body  that  contained  it. 

This  is  shown  by  some  of  the  following  experiments. 

III.  Bodies  electrified  negatively,  or  deprived  of 
their  natural  quantity  of  electricity,  repel  each  other 
(or  at  least  appear  to  do  so  by  a  mutual  receding) ,  as 

5 


6 


Benjamin  Franklin 


[1755 


well  as  those  electrified  positively,  or  which  have 
electric  atmospheres. 

This  is  shown  by  applying  the  negatively  charged 
wire  of  a  phial  to  two  cork  balls  suspended  by  silk 
threads,  and  many  other  experiments. 

Fix  a  tassel  of  fifteen  or  twenty  threads,  three 
inches  long,  at  one  end  of  a  tin  prime  conductor 
(mine  is  about  five  feet  long  and  four  inches  diameter) 
supported  by  silk  lines. 

Let  the  threads  be  a  little  damp,  but  not  wet. 

Pass  an  excited  glass  tube  near  the  other  end  of  the 
prime  conductor,  so  as  to  give  it  some  sparks,  and  the 
threads  will  diverge. 

Because  each  thread,  as  well  as  the  prime  con- 
ductor, has  acquired  an  electric  atmosphere,  which 
repels  and  is  repelled  by  the  atmospheres  of  the  other 
threads ;  if  those  several  atmospheres  would  readily 
mix,  the  threads  might  unite,  and  hang  in  the  middle 
of  one  atmosphere,  common  to  them  all. 

Rub  the  tube  afresh,  and  approach  the  prime  conductor 
therewith,  crosswise,  near  that  end,  but  not  nigh  enough 
to  give  sparks,  and  the  threads  will  diverge  a  little  more. 

Because  the  atmosphere  of  the  prime  conductor  is 
pressed  by  the  atmosphere  of  the  excited  tube,  and 
driven  towards  the  end  where  the  threads  are,  by 
which  each  thread  acquires  more  atmosphere. 

Withdraw  the  tube,  and  they  will  close  as  much. 

They  close  as  much,  and  no  more,  because  the  at- 
mosphere of  the  glass  tube,  not  having  mixed  with 
the  atmosphere  of  the  prime  conductor,  is  withdrawn 
entire,  having  made  no  addition  to  or  diminution 
from  it. 


755] 


Essays 


7 


Bring  the  excited  tube  under  the  tuft  of  threads,  and 
they  will  close  a  little. 

They  close,  because  the  atmosphere  of  the  glass 
tube  repels  their  atmospheres,  and  drives  part  of 
them  back  on  the  prime  conductor. 

Withdraw  it,  and  they  will  diverge  as  much. 

For  the  portion  of  atmosphere  which  they  had  lost 
returns  to  them  again. 

Excite  the  glass  tube  and  approach  the  prime  con- 
ductor with  it,  holding  it  across,  near  the  end  opposite  to 
that  on  which  the  threads  hang,  at  the  distance  of  five  or 
six  inches.  Keep  it  there  a  few  seconds,  and  the  threads 
of  the  tassels  will  diverge.  Withdraw  it,  and  they  will 
close. 

They  diverge,  because  they  have  received  electric 
atmospheres  from  the  electric  matter  before  con- 
tained in  the  substance  of  the  prime  conductor,  but 
which  is  now  repelled  and  driven  away  by  the  atmos- 
phere of  the  glass  tube  from  the  parts  of  the  prime 
conductor  opposite  and  nearest  to  that  atmosphere, 
and  forced  out  upon  the  surface  of  the  prime  con- 
ductor at  its  other  end,  and  upon  the  threads  hanging 
thereto.  Were  it  any  part  of  the  atmosphere  of  the 
glass  tube  that  flowed  over  and  along  the  prime  con- 
ductor to  the  threads,  and  gave  them  atmospheres 
(as  is  the  case  when  a  spark  is  given  to  the  prime 
conductor  from  the  glass  tube),  such  part  of  the 
tube's  atmosphere  would  have  remained,  and  the 
threads  continue  to  diverge ;  but  they  close  on  with- 
drawing the  tube,  because  the  tube  takes  with  it  all  its 
own  atmosphere,  and  the  electric  matter,  which  had 
been  driven  out  of  the  substance  of  the  prime  con- 


8  Benjamin  Franklin 


[1755 


ductor,  and  formed  atmospheres  round  the  threads, 
is  thereby  permitted  to  return  to  its  place. 

Take  a  spark  from  the  prime  conductor  near  the 
threads,  when  they  are  diverged  as  before,  and  they  will 
close. 

For  by  so  doing  you  take  away  their  atmospheres, 
composed  of  the  electric  matter  driven  out  of  the 
substance  of  the  prime  conductor,  as  aforesaid,  by  the 
repellency  of  the  atmosphere  of  the  glass  tube.  By 
taking  this  spark  you  rob  the  prime  conductor  of  part 
of  its  natural  quantity  of  the  electric  matter,  which 
part  so  taken  is  not  supplied  by  the  glass  tube,  for, 
when  that  is  afterwards  withdrawn,  it  takes  with 
it  its  whole  atmosphere,  and  leaves  the  prime  con- 
ductor electrized  negatively,  as  appears  by  the  next 
operation. 

Then  withdraw  the  tube,  and  they  will  open  again. 

For  now  the  electric  matter  in  the  prime  conductor' 
returning  to  its  equilibrium,  or  equal  diffusion,  in 
all  parts  of  its  substance,  and  the  prime  conductor 
having  lost  some  of  its  natural  quantity,  the  threads 
connected  with  it  lose  part  of  theirs,  and  so  are  elec- 
trized negatively,  and  therefore  repel  each  other,  by 
Principle  III. 

Approach  the  prime  conductor  with  the  tube,  near  the 
same  place  as  at  first,  and  they  will  close  again. 

Because  the  part  of  their  natural  quantity  of  elec- 
tric fluid  which  they  had  lost  is  now  restored  to  them 
again,  by  the  repulsion  of  the  glass  tube  forcing  that 
fluid  to  them  from  other  parts  of  the  prime  conductor; 
so  they  are  now  again  in  their  natural  state. 

Withdraw  it,  and  they  will  open  again. 


755] 


Essays 


9 


For  what  had  been  restored  to  them  is  now  taken 
from  them  again,  flowing  back  into  the  prime  con- 
ductor, and  leaving  them  once  more  electrized 
negatively. 

Bring  the  excited  tube  under  the  threads,  and  they 
will  diverge  more. 

Because  more  of  their  natural  quantity  is  driven 
from  them  into  the  prime  conductor,  and  thereby 
their  negative  electricity  increased. 

The  prime  conductor  not  being  electrified,  brings  the 
excited  tube  under  the  tassel,  and  the  threads  will  diverge. 

Part  of  their  natural  quantity  is  thereby  driven  out 
of  them  into  the  prime  conductor,  and  they  become 
negatively  electrized,  and  therefore  repel  each  other. 

Keeping  the  tube  in  the  same  place  with  one  hand, 
attempt  to  touch  the  threads  with  the  finger  of  the  other 
hand,  and  they  will  recede  from  the  finger. 

Because  the  finger  being  plunged  into  the  atmos- 
phere of  the  glass  tube,  as  well  as  the  threads,  part 
of  its  natural  quantity  is  driven  back  through  the 
hand  and  body  by  that  atmosphere,  and  the  finger 
becomes,  as  well  as  the  threads,  negatively  electrized, 
and  so  repels,  and  is  repelled  by  them.  To  confirm 
this,  hold  a  slender,  light  lock  of  cotton,  two  or  three 
inches  long,  near  a  prime  conductor  that  is  electrified 
by  a  glass  globe  or  tube.  You  will  see  the  cotton 
stretch  itself  out  towards  the  prime  conductor.,  At- 
tempt to  touch  it  with  the  finger  of  the  other  hand, 
and  it  will  be  repelled  by  the  finger.  Approach  it 
with  a  positively  charged  wire  of  a  bottle,  and  it  will 
fly  to  the  wire.  Bring  it  near  a  negatively  charged 
wire  of  a  bottle,  it  will  recede  from  that  wire  in  the 


io  Benjamin  Franklin  [1755 

same  manner  that  it  did  from  the  finger;  which 
demonstrates  the  finger  to  be  negatively  electrized, 
as  well  as  the  lock  of  cotton  so  situated. 


Turkey  killed  by  Electricity. — Effect  of  a  Shock  on  the 
Operator  in  making  the  Experiment 

As  Mr.  Franklin,  in  a  former  letter  to  Mr.  Collin- 
son,  mentioned  his  intending  to  try  the  power  of  a 
very  strong  electrical  shock  upon  a  turkey,  that  gen- 
tleman accordingly  has  been  so  very  obliging  as 
to  send  an  account  of  it,  which  is  to  the  following 
purpose: 

He  made  first  several  experiments  on  fowls,  and 
found  that  two  large,  thin  glass  jars  gilt,  holding 
each  about  six  gallons,  were  sufficient,  when  fully 
charged,  to  kill  common  hens  outright;  but  the 
turkeys,  though  thrown  into  violent  convulsions, 
and  then  lying  as  dead  for  some  minutes,  would 
recover  in  less  than  a  quarter  of  an  hour.  However, 
having  added  three  other  such  to  the  former  two, 
though  not  fully  charged,  he  killed  a  turkey  of  about 
ten  pounds  weight,  and  believes  that  they  would 
have  killed  a  much  larger.  He  conceited,  as  him- 
self says,  that  the  birds  killed  in  this  manner  eat  un- 
commonly tender. 

In  making  these  experiments,  he  found  that  a 
man  could,  without  great  detriment,  bear  a  much 
greater  shock  than  he  had  imagined;  for  he  inad- 
vertently received  the  stroke  of  two  of  these  jars 
through  his  arms  and  body,  when  they  were  very 


1755] 


Essays 


ii 


near  fully  charged.  It  seemed  to  him  a  universal 
blow  throughout  the  body  from  head  to  foot,  and 
was  followed  by  a  violent,  quick  trembling  in  the 
trunk  which  went  off  gradually  in  a  few  seconds. 
It  was  some  minutes  before  he  could  recollect  his 
thoughts  so  as  to  know  what  was  the  matter;  -for  he 
did  not  see  the  flash,  though  his  eye  was  on  the  spot 
of  the  prime  conductor,  from  whence  it  struck  the 
back  of  his  hand;  nor  did  he  hear  the  crack,  though 
the  by-standers  said  it  was  a  loud  one;  nor  did  he 
particularly  feel  the  stroke  on  his  hand,  though  he 
afterwards  found  it  had  raised  a  swelling  there  of 
the  bigness  of  half  a  pistol-bullet.  His  arms  and 
the  back  of  the  neck  felt  somewhat  numbed  the  re- 
mainder of  the  evening,  and  his  breast  was  sore  for 
a  week  after,  as  if  it  had  been  bruised.  From  this 
experiment  may  be  seen  the  danger,  even  under  the 
greatest  caution,  to  the  operator,  when  making  these 
experiments  with  large  jars;  for  it  is  not  to  be 
doubted  but  several  of  these  fully  charged  would  as 
certainly,  by  increasing  them  in  proportion  to  the 
size,  kill  a  man,  as  they  before  did  a  turkey. 


Ill 


TO  JOHN  LINING,  AT  CHARLESTON,  SOUTH  CAROLINA 

Philadelphia,  18  March,  1755. 

Sir: — I  send  you  enclosed  a  paper  containing 
some  new  experiments  I  have  made,  in  pursuance  of 
those  by  Mr.  Canton,  that  are  printed  with  my  last 
letters.  I  hope  these,  with  my  explanation  of  them, 
will  afford  you  some  entertainment.1 

In  answer  to  your  several  inquiries.  The  tubes 
and  globes  we  use  here  are  chiefly  made  here.  The 
glass  has  a  greenish  cast,  but  is  clear  and  hard,  and, 
I  think,  better  for  electrical  experiments  than  the 
white  glass  of  London,  which  is  not  so  hard.  There 
are  certainly  great  differences  in  glass.  A  white 
globe  I  had  made  here  some  years  since,  would  never, 
by  any  means,  be  excited.  Two  of  my  friends  tried 
it,  as  well  as  myself,  without  success.  At  length, 
putting  it  on  an  electric  stand,  a  chain  from  the 
prime  conductor  being  in  contact  with  it,  I  found  it 
had  the  properties  of  a  non-electric ;  for  I  could  draw 
sparks  from  any  part  of  it,  though  it  was  very  clean 
and  dry. 

All  I  know  of  Domien  is,  that  by  his  own  account 
he  was  a  native  of  Transylvania,  of  Tartar  descent, 
but  a  priest  of  the  Greek  Church;  he  spoke  and 

1  See  No.  II. 

12 


1755] 


Essays 


13 


wrote  Latin  very  readily  and  correctly.  He  set  out 
from  his  own  country  with  an  intention  of  going 
round  the  world,  as  much  as  possible  by  land.  He 
travelled  through  Germany,  France,  and  Holland, 
to  England.  Resided  some  time  at  Oxford.  From 
England  he  came  to  Maryland;  thence  went  to  New 
England;  returned  by  land  to  Philadelphia;  and 
from  hence  travelled  through  Maryland,  Virginia, 
and  North  Carolina  to  you.  He  thought  it  might 
be  of  service  to  him  in  his  travels  to  know  something 
of  electricity.  I  taught  him  the  use  of  the  tube,  how 
to  charge  the  Leyden  phial,  and  some  other  experi- 
ments. He  wrote  to  me  from  Charleston,  that  he 
lived  eight  hundred  miles  upon  electricity;  it  had 
been  meat,  drink,  and  clothing  to  him.  His  last 
letter  to  me  was,  I  think,  from  Jamaica,  desiring  me 
to  send  the  tubes  you  mention,  to  meet  him  at  the 
Havana,  from  whence  he  expected  to  get  a  passage 
to  La  Vera  Cruz;  designed  travelling  over  land 
through  Mexico  to  Acapulco ;  thence  to  get  a  passage 
to  Manilla,  and  so  through  China,  India,  Persia,  and 
Turkey,  home  to  his  own  country,  proposing  to  sup- 
port himself  chiefly  by  electricity.  A  strange  pro- 
ject! But  he  was,  as  you  observe,  a  very  singular 
character.  I  was  sorry  the  tubes  did  not  get  to  the 
Havana  in  time  for  him.  If  they  are  still  in  being, 
please  to  send  for  them,  and  accept  of  them.  What 
became  of  him  afterwards,  I  have  never  heard.  He 
promised  to  write  to  me  as  often  as  he  could  on  his 
journey,  and  as  soon  as  he  should  get  home  after 
finishing  his  tour.  It  is  now  seven  years  since  he 
was  here.    If  he  is  still  in  New  Spain,  as  you  im- 


14  Benjamin  Franklin  [1755 

agine  from  that  loose  report,  I  suppose  it  must  be 
that  they  confine  him  there,  and  prevent  his  writing ; 
but  I  think  it  more  likely  that  he  may  be  dead. 

The  questions  you  ask  about  the  pores  of  glass,  I 
cannot  answer  otherwise  than  that  I  know  nothing 
of  their  nature ;  and  suppositions,  however  ingenious, 
are  often  mere  mistakes.  My  hypothesis,  that  they 
were  smaller  near  the  middle  of  the  glass, — too  small 
to  admit  the  passage  of  electricity,  which  could  pass 
through  the  surface  till  it  came  near  the  middle, 
was  certainly  wrong.  For  soon  after  I  had  written 
that  letter,  I  did,  in  order  to  confirm  the  hypothesis 
(which  indeed  I  ought  to  have  done  before  I  wrote 
it),  make  an  experiment.  I  ground  away  five  sixths 
of  the  thickness  of  the  glass  from  the  side  of  one  of 
my  phials,  expecting  that,  the  supposed  denser  part 
being  so  removed,  the  electric  fluid  might  come 
through  the  remainder  of  the  glass,  which  I  had 
imagined  more  open;  but  I  found  myself  mistaken. 
The  bottle  charged  as  well  after  the  grinding  as  be- 
fore. I  am  now  as  much  as  ever  at  a  loss  to  know 
how  or  where  the  quantity  of  electric  fluid  on  the 
positive  side  of  the  glass  is  disposed  of. 

As  to  the  difference  of  conductors,  there  is  not 
only  this,  that  some  will  conduct  electricity  in  small 
quantities,  and  yet  do  not  conduct  it  fast  enough  to 
produce  the  shock ;  but  even  among  those  that  will 
conduct  a  shock,  there  are  some  that  do  it  better  than 
others.  Mr.  Kinnersley  has  found,  by  a  very  good 
experiment,  that  when  the  charge  of  a  bottle  hath  an 
opportunity  of  passing  two  ways,  that  is,  straight 
through  a  trough  of  water  ten  feet  long  and  six 


1755] 


Essays 


15 


inches  square,  or  round  about  through  twenty  feet 
of  wire,  it  passes  through  the  wire,  and  not  through 
the  water,  though  that  is  the  shortest  course;  the 
wire  being  the  better  conductor.  When  the  wire  is 
taken  away,  it  passes  through  the  water,  as  may  be 
felt  by  a  hand  plunged  in  the  water;  but  it  cannot 
be  felt  in  the  water  when  the  wire  is  used  at  the  same 
time.  Thus,  though  a  small  phial  containing  water 
will  give  a  smart  shock,  one  containing  the  same 
quantity  of  mercury  will  give  one  much  stronger,  the 
mercury  being  the  better  conductor;  while  one  con- 
taining oil  only,  will  scarce  give  any  shock  at  all. 

Your  question,  how  I  came  first  to  think  of  pro- 
posing the  experiment  of  drawing  down  the  light- 
ning in  order  to  ascertain  its  sameness  with  the  elec- 
tric fluid,  I  cannot  answer  better  than  by  giving  you 
an  extract  from  the  minutes  I  used  to  keep  of  the 
experiments  I  made,  with  memorandums  of  such  as 
I  purposed  to  make,  the  reasons  for  making  them, 
and  the  observations  that  arose  upon  them,  from 
which  minutes  my  letters  were  afterwards  drawn. 
By  this  extract  you  will  see  that  the  thought  was 
not  so  much  "an  out-of-the-way  one,"  but  that  it 
might  have  occurred  to  an  electrician. 

"  November  yth,  1749.  Electrical  fluid  agrees  with 
lightning  in  these  particulars:  1.  Giving  light.  2. 
Color  of  the  light.  3.  Crooked  direction.  4.  Swift 
motion.  5.  Being  conducted  by  metals.  6.  Crack 
or  noise  in  exploding.  7.  Subsisting  in  water  or  ice. 
8.  Rending  bodies  it  passes  through.  9.  Destroying 
animals.  10.  Melting  metals.  11.  Firing  inflam- 
mable substances.   12.  Sulphureous  smell.  Theelec- 


1 6  Benjamin  Franklin  [1755 

trie  fluid  is  attracted  by  points.  We  do  not  know 
whether  this  property  is  in  lightning.  But  since 
they  agree  in  all  the  particulars  wherein  we  can 
already  compare  them,  is  it  not  probable  they  agree 
likewise  in  this?    Let  the  experiment  be  made." 

I  wish  I  could  give  you  any  satisfaction  in  the 
article  of  clouds.  I  am  still  at  a  loss  about  the  man- 
ner in  which  they  become  charged  with  electricity; 
no  hypothesis  I  have  yet  formed  perfectly  satisfying 
me.  Some  time  since,  I  heated  very  hot  a  brass 
plate,  two  feet  square,  and  placed  it  on  an  electric 
stand.  From  the  plate  a  wire  extended  horizontally 
four  or  five  feet,  and,  at  the  end  of  it,  hung,  by  linen 
threads,  a  pair  of  cork  balls.  I  then  repeatedly 
sprinkled  water  over  the  plate,  that  it  might  be 
raised  from  it  in  vapor,  hoping,  that,  if  the  vapor 
either  carried  off  the  electricity  of  the  plate,  or  left 
behind  it  that  of  the  water  (one  of  which  I  sup- 
posed it  must  do,  if,  like  the  clouds,  it  became  elec- 
trized itself,  either  positively  or  negatively),  I  should 
perceive  and  determine  it  by  the  separation  of  the 
balls,  and  by  finding  whether  they  were  positive  or 
negative;  but  no  alteration  was  made  at  all,  nor 
could  I  perceive  that  the  steam  was  itself  electrized, 
though  I  have  still  some  suspicion  that  the  steam 
was  not  fully  examined,  and  I  think  the  experiment 
should  be  repeated.  Whether  the  first  state  of  elec- 
trized clouds  is  positive  or  negative,  if  I  could  find 
the  cause  of  that,  I  should  be  at  no  loss  about  the 
other ;  for  either  is  easily  deduced  from  the  other,  as 
one  state  is  easily  produced  by  the  other.  A  strongly 
positive  cloud  may  drive  out  of  a  neighbouring 


1755] 


Essays 


17 


cloud  much  of  its  natural  quantity  of  the  electric 
fluid,  and,  passing  by  it,  leave  it  in  a  negative  state. 
In  the  same  way,  a  strongly  negative  cloud  may 
occasion  a  neighbouring  cloud  to  draw  into  itself 
from  others  an  additional  quantity,  and,  passing  by 
it,  leave  it  in  a  positive  state.  How  these  effects 
may  be  produced,  you  will  easily  conceive,  on  perus- 
ing and  considering  the  experiments  in  the  enclosed 
paper;  and  from  them  too  it  appears  probable,  that 
every  change  from  positive  to  negative,  and  from 
negative  to  positive,  that,  during  a  thunder-gust,  we 
see  in  the  cork  balls  annexed  to  the  apparatus,  is  not 
owing  to  the  presence  of  clouds  in  the  same  state, 
but  often  to  the  absence  of  positive  or  negative 
clouds,  that,  having  just  passed,  leave  the  rod  in  the 
opposite  state. 

The  knocking  down  of  the  six  men  was  performed 
with  two  of  my  large  jars  not  fully  charged.  I  laid 
one  end  of  my  discharging-rod  upon  the  head  of  the 
first;  he  laid  his  hand  on  the  head  of  the  second;  the 
second  his  hand  on  the  head  of  the  third,  and  so  to 
the  last,  who  held  in  his  hand  the  chain  that  was 
connected  with  the  outside  of  the  jars.  When  they 
were  thus  placed,  I  applied  the  other  end  of  my  rod 
to  the  prime  conductor,  and  they  all  dropped  to- 
gether. When  they  got  up,  they  all  declared  they 
had  not  felt  any  stroke,  and  wondered  how  they  came 
to  fall ;  nor  did  any  of  them  either  hear  the  crack,  or 
see  the  light  of  it.  You  suppose  it  a  dangerous  ex- 
periment; but  I  had  once  suffered  the  same  myself, 
receiving,  by  accident,  an  equal  stroke  through  my 
head,  that  struck  me  down,  without  hurting  me. 


i8 


Benjamin  Franklin 


ti755 


And  I  had  seen  a  young  woman,  that  was  about  to 
be  electrified  through  the  feet  (for  some  indisposition) 
receive  a  greater  charge  through  the  head,  by  in- 
advertently stooping  forward  to  look  at  the  placing 
of  her  feet,  till  her  forehead  (as  she  was  very  tall) 
came  too  near  my  prime  conductor;  she  dropped, 
but  instantly  got  up  again,  complaining  of  nothing. 
A  person  so  struck,  sinks  down  doubled,  or  folded 
together,  as  it  were,  the  joints  losing  their  strength 
and  stiffness  at  once,  so  that  he  drops  on  the  spot 
where  he  stood,  instantly,  and  there  is  no  previous 
staggering,  nor  does  he  ever  fall  lengthwise.  Too 
great  a  charge  might,  indeed,  kill  a  man,  but  I  have 
not  yet  seen  any  hurt  done  by  it.  It  would  cer- 
tainly, as  you  observe,  be  the  easiest  of  all  deaths. 

The  experiment  you  have  heard  so  imperfect  an 
account  of,  is  merely  this :  I  electrified  a  silver  pint 
can,  on  an  electric  stand,  and  then  lowered  into  it  a 
cork  ball,  of  about  an  inch  diameter,  hanging  by 
a  silk  string,  till  the  cork  touched  the  bottom  of  the 
can.  The  cork  was  not  attracted  to  the  inside  of 
the  can,  as  it  would  have  been  to  the  outside;  and, 
though  it  touched  the  bottom,  yet,  when  drawn  out, 
it  was  not  found  to  be  electrified  by  that  touch,  as  it 
would  have  been  by  touching  the  outside.  The 
fact  is  singular.  You  require  the  reason;  I  do  not 
know  it.  Perhaps  you  may  discover  it,  and  then 
you  will  be  so  good  as  to  communicate  it  to  me.1  I 

1  Mr.  Franklin  has  since  thought,  that  possibly  the  mutual  repulsion 
of  the  inner  opposite  sides  of  the  electrical  can  may  prevent  the  ac- 
cumulating an  electric  atmosphere  upon  them,  and  occasion  it  to 
stand  chiefly  on  the  outside;  but  recommends  it  to  the  farther  exam- 
ination of  the  curious. 


1755] 


Essays 


19 


find  a  frank  acknowledgment  of  one's  ignorance  is, 
not  only  the  easiest  way  to  get  rid  of  a  difficulty,  but 
the  likeliest  way  to  obtain  information,  and  there- 
fore I  practise  it ;  I  think  it  an  honest  policy.  Those 
who  affect  to  be  thought  to  know  every  thing, 
and  so  undertake  to  explain  every  thing,  often  re- 
main long  ignorant  of  many  things  that  others  could 
and  would  instruct  them  in,  if  they  appeared  less 
conceited. 

The  treatment  your  friend  has  met  with  is  so  com- 
mon, that  no  man,  who  knows  what  the  world  is  and 
ever  has  been,  should  expect  to  escape  it.  There 
are  everywhere  a  number  of  people,  who,  being 
totally  destitute  of  any  inventive  faculty  them- 
selves, do  not  readily  conceive  that  others  may  pos- 
sess it ;  they  think  of  inventions  as  of  miracles ;  there 
might  be  such  formerly,  but  they  are  ceased.  With 
these,  every  one  who  offers  a  new  invention  is  deemed 
a  pretender;  he  had  it  from  some  other  country,  or 
from  some  book;  a  man  of  their  own  acquaintance, 
one  who  has  no  more  sense  than  themselves,  could 
not  possibly,  in  their  opinion,  have  been  the  inventor 
of  any  thing.  They  are  confirmed,  too,  in  these 
sentiments,  by  frequent  instances  of  pretensions  to 
invention,  which  vanity  is  daily  producing.  That 
vanity,  too,  though  an  incitement  to  invention,  is, 
at  the  same  time,  the  pest  of  inventors.  Jealousy 
and  envy  deny  the  merit  or  the  novelty  of  your  in- 
vention ;  but  vanity,  when  the  novelty  and  merit  are 
established,  claims  it  for  its  own.  The  smaller  your 
invention  is,  the  more  mortification  you  receive  in 
having  the  credit  of  it  disputed  with  you  by  a  rival, 


20 


Benjamin  Franklin 


[1755 


whom  the  jealousy  and  envy  of  others  are  ready  to 
support  against  you,  at  least  so  far  as  to  make  the 
point  doubtful.  It  is  not  in  itself  of  importance 
enough  for  a  dispute;  no  one  would  think  your 
proofs  and  reasons  worth  their  attention;  and  yet, 
if  you  do  not  dispute  the  point,  and  demonstrate 
your  right,  you  not  only  lose  the  credit  of  being  in 
that  instance  ingenious,  but  you  suffer  the  disgrace 
of  not  being  ingenuous;  not  only  of  being  a  plagiary, 
but  of  being  plagiary  for  trifles.  Had  the  invention 
been  greater,  it  would  have  disgraced  you  less;  for 
men  have  not  so  contemptible  an  idea  of  him  that 
robs  for  gold  on  the  highway,  as  of  him  that  can  pick 
pockets  for  half- pence  and  farthings.  Thus,  through 
envy,  jealousy,  and  the  vanity  of  competitors  for 
fame,  the  origin  of  many  of  the  most  extraordinary 
inventions,  though  produced  within  but  a  few  cen- 
turies past,  is  involved  in  doubt  and  uncertainty. 
We  scarce  know  to  whom  we  are  indebted  for  the 
compass,  and  spectacles,  nor  have  even  paper  and 
printing,  that  record  every  thing  else,  been  able  to 
preserve  with  certainty  the  name  and  reputation  of 
their  inventors.  One  would  not,  therefore,  of  all 
faculties  or  qualities  of  the  mind,  wish,  for  a  friend 
or  a  child,  that  he  should  have  that  of  invention. 
For  his  attempts  to  benefit  mankind  in  that  way, 
however  well  imagined,  if  they  do  not  succeed,  ex- 
pose him,  though  very  unjustly,  to  general  ridicule 
and  contempt;  and,  if  they  do  succeed,  to  envy, 
robbery,  and  abuse. 

I  am,  &c, 

B.  Franklin. 


IV 


TO  JOHN  PRINGLE 

Craven  Street,  6  January,  1758. 

Sir: — I  return  you  Mr.  Mitchell's  paper  on  the 
strata  of  the  earth,  with  thanks.  The  reading  of  it, 
and  perusal  of  the  draft  that  accompanies  it,  have 
reconciled  me  to  those  convulsions  which  all  natural- 
ists agree  this  globe  has  suffered.  Had  the  different 
strata  of  clay,  gravel,  marble,  coals,  limestone,  sand, 
minerals,  &c,  continued  to  lie  level,  one  under  the 
other,  as  they  may  be  supposed  to  have  done  before 
those  convulsions,  we  should  have  had  the  use  only 
of  a  few  of  the  uppermost  of  the  strata,  the  others 
lying  too  deep  and  too  difficult  to  be  come  at ;  but,  the 
shell  of  the  earth  being  broke,  and  the  fragments 
thrown  into  this  oblique  position,  the  disjointed  ends 
of  a  great  number  of  strata  of  different  kinds  are 
brought  up  to  day,  and  a  great  variety  of  useful 
materials  put  into  our  power,  which  would  otherwise 
have  remained  eternally  concealed  from  us.  So  that 
what  has  been  usually  looked  upon  as  a  ruin  suffered 
by  this  part  of  the  universe,  was,  in  reality,  only  a 
preparation,  or  means  of  rendering  the  earth  more 
fit  for  use,  more  capable  of  being  to  mankind  a  con- 
venient and  comfortable  habitation. 

I  am,  Sir,  with  great  esteem,  yours,  &c, 

B.  Franklin. 

21 


V 


TO  JOHN  LINING,  AT  CHARLESTON 

London,  17  June,  1758. 

Dear  Sir: — In  a  former  letter  I  mentioned  the 
experiment  for  cooling  bodies  by  evaporation,  and 
that  I  had,  by  repeatedly  wetting  the  thermometer 
with  common  spirits,  brought  the  mercury  down  five 
or  six  degrees.  Being  lately  at  Cambridge,  and  men- 
tioning this  in  conversation  with  Dr.  Hadley,  pro- 
fessor of  chemistry  there,  he  proposed  repeating  the 
experiments  with  ether,  instead  of  common  spirits  as 
the  ether  is  much  quicker  in  evaporation.  We  ac- 
cordingly went  to  his  chamber,  where  he  had  both 
ether  and  a  thermometer.  By  dipping  first  the  ball 
of  the  thermometer  into  the  ether,  it  appeared  that 
the  ether  was  precisely  of  the  same  temperament 
with  the  thermometer,  which  stood  then  at  65;  for 
it  made  no  alteration  in  the  height  of  the  little  col- 
umn of  mercury.  But  when  the  thermometer  was 
taken  out  of  the  ether,  and  the  ether,  with  which  the 
ball  was  wet,  began  to  evaporate,  the  mercury  sunk 
several  degrees.  The  wetting  was  then  repeated  by 
22 


1758] 


Essays 


23 


a  feather  that  had  been  dipped  into  the  ether,  when 
the  mercury  sunk  still  lower. 

We  continued  this  operation,  one  of  us  wetting 
the  ball,  and  another  of  the  company  blowing  on  it 
with  the  bellows  to  quicken  the  evaporation,  the 
mercury  sinking  all  the  time,  till  it  came  down  to  7, 
which  is  25  degrees  below  the  freezing  point,  when  we 
left  off.  Soon  after  it  passed  the  freezing  point  a 
thin  coat  of  ice  began  to  cover  the  ball.  Whether 
this  was  water  collected  and  condensed  by  the  cold- 
ness of  the  ball  from  the  moisture  in  the  air  or  from 
our  breath;  or  whether  the  feather,  when  dipped 
into  the  ether,  might  not  sometimes  go  through  it 
and  bring  up  some  of  the  water  that  was  under  it,  I 
am  not  certain;  perhaps  all  might  contribute.  The 
ice  continued  increasing  till  we  ended  the  experi- 
ment, when  it  appeared  near  a  quarter  of  an  inch 
thick  all  over  the  ball,  with  a  number  of  small  spic- 
ula,  pointing  outwards.  From  this  experiment  one 
may  see  the  possibility  of  freezing  a  man  to  death  on 
a  warm  summer's  day,  if  he  were  to  stand  in  a  pas- 
sage through  which  the  wind  blew  briskly,  and  to  be 
wet  frequently  with  ether,  a  spirit  that  is  more 
inflammable  than  brandy  or  common  spirits  of 
wine. 

It  is  but  within  these  few  years  that  the  European 
philosophers  seem  to  have  known  this  power  in  na- 
ture, of  cooling  bodies  by  evaporation.  But  in  the 
east  they  have  long  been  acquainted  with  it.  A 
friend  tells  me  there  is  a  passage  in  Bernier's  Travels 
through  Indostan,  written  near  one  hundred  years 


24  Benjamin  Franklin  [1758 

ago,  that  mentions  it  as  a  practice  (in  travelling  over 
dry  deserts  in  that  hot  climate)  to  carry  water  in 
flasks  wrapped  in  wet  woollen  cloths,  and  hung  on 
the  shady  side  of  the  camel,  or  carriage,  but  in  the 
free  air;  whereby,  as  the  cloths  gradually  grow  drier, 
the  water  contained  in  the  flasks  is  made  cool.  They 
have  likewise  a  kind  of  earthen  pots,  unglazed, 
which  let  the  water  gradually  and  slowly  ooze 
through  their  pores,  so  as  to  keep  the  outside  a  little 
wet,  notwithstanding  the  continual  evaporation, 
which  gives  great  coldness  to  the  vessel  and  the 
water  contained  in  it.  Even  our  common  sailors 
seem  to  have  had  some  notion  of  this  property;  for 
I  remember  that,  being  at  sea  when  I  was  a  youth, 
I  observed  one  of  the  sailors,  during  a  calm  in  the 
night,  often  wetting  his  finger  in  his  mouth,  and  then 
holding  it  up  in  the  air,  to  discover,  as  he  said,  if  the 
air  had  any  motion,  and  from  which  side  it  came; 
and  this  he  expected  to  do  by  finding  one  side  of  his 
finger  grow  suddenly  cold,  and  from  that  side  he 
should  look  for  the  next  wind ;  which  I  then  laughed 
at  as  a  fancy. 

May  not  several  phenomena  hitherto  unconsid- 
ered or  unaccounted  for  be  explained  by  this  prop- 
erty? During  the  hot  Sunday  at  Philadelphia,  in 
June,  1750,  when  the  thermometer  was  up  at  100 
in  the  shade,  I  sat  in  my  chamber  wi'hout  exercise, 
only  reading  or  writing,  with  no  other  clothes  on  than 
a  shirt  and  a  pair  of  long  linen  drawers,  the  windows 
all  open,  and  a  brisk  wind  blowing  through  the 
house;  the  sweat  ran  off  the  backs  of  my  hands,  and 
my  shirt  was  often  so  wet  as  to  induce  me  to  call  for 


1758] 


Essays 


25 


!  dry  ones  to  put  on.    In  this  situation,  one  might 
I  have  suspected  that  the  natural  heat  of  the  body, 
96,  added  to  the  heat  of  the  air,  100,  should  jointly 
I  have  created  or  produced  a  much  greater  degree  of 
I  heat  in  the  body;  but  the  fact  was  that  my  body 
never  grew  so  hot  as  the  air  that  surrounded  it,  or 
the  inanimate  bodies  immersed  in  the  same  air.  For 
I  remember  well  that  the  desk,  when  I  laid  my  arm 
upon  it;  a  chair,  when  I  sat  down  in  it;  and  a  dry- 
shirt  out  of  the  drawer,  when  I  put  it  on — all  felt 
exceeding  warm  to  me,  as  if  they  had  been  warmed 
before  a  fire.    And  I  suppose  a  dead  body  would 
have  acquired  the  temperature  of  the  air,  though  a 
living  one,  by  continual  sweating,  and  by  the  eva- 
poration of  that  sweat,  was  kept  cold. 

May  not  this  be  a  reason  why  our  reapers  in  Penn- 
sylvania, working  in  the  open  field  in  the  clear  hot 
sunshine  common  in  our  harvest- time,1  find  them- 
selves well  able  to  go  through  that  labor  without 
being  much  incommoded  by  the  heat,  while  they 
continue  to  sweat,  and  while  they  supply  matter  for 
keeping  up  that  sweat,  by  drinking  frequently  of  a 
thin  evaporable  liquor,  water  mixed  with  rum;  but, 
if  the  sweat  stops,  they  drop,  and  sometimes  die  sud- 
denly, if  a  sweating  is  not  again  brought  on  by  drink- 
ing that  liquor,  or,  as  some  rather  choose  in  that 
case,  a  kind  of  hot  punch,  made  with  water,  mixed 
with  honey,  and  a  considerable  proportion  of  vinegar? 

1  Pennsylvania  is  in  about  lat.  40,  and  the  sun,  of  course,  about  1 2 
degrees  higher,  and  therefore  much  hotter,  than  in  England.  Their 
harvest  is  about  the  end  of  June  or  beginning  of  July,  when  the  sun  is 
nearly  at  the  highest. — F. 


26 


Benjamin  Franklin 


[1758 


May  there  not  be  in  negroes  a  quicker  evapora- 
tion of  the  perspirable  matter  from  their  skins  and 
lungs,  which,  by  cooling  them  more,  enables  them  to 
bear  the  sun's  heat  better  than  whites  do?  (if  that  is 
a  fact,  as  it  is  said  to  be ;  for  the  alleged  necessity  of 
having  negroes  rather  than  whites  to  work  in  the 
West  India  fields  is  founded  upon  it,)  though  the 
color  of  their  skins  would  otherwise  make  them  more 
sensible  of  the  sun's  heat,  since  black  ploth  heats 
much  sooner  and  more,  in  the  sun,  than  white  cloth. 
I  am  persuaded,  from  several  instances  happening 
within  my  knowledge,  that  they  do  not  bear  cold 
weather  so  well  as  the  whites ;  they  will  perish  when 
exposed  to  a  less  degree  of  it,  and  are  more  apt  to 
have  their  limbs  frost-bitten;  and  may  not  this  be 
from  the  same  cause? 

Would  not  the  earth  grow  much  hotter  under  the 
summer  sun  if  a  constant  evaporation  from  its  sur- 
face, greater  as  the  sun  shines  stronger,  did  not,  by 
tending  to  cool  it,  balance,  in  some  degree,  the 
warmer  effects  of  the  sun's  rays?  Is  it  not  owing  to 
the  constant  evaporation  from  the  surface  of  every 
leaf,  that  trees,  though  shone  on  by  the  sun,  are 
always,  even  the  leaves  themselves,  cool  to  our 
sense?  at  least  much  cooler  than  they  would  other- 
wise be?  May  it  not  be  owing  to  this  that,  fanning 
ourselves  when  warm,  does  really  cool  us,  though  the 
air  is  itself  warm  that  we  drive  with  the  fan  upon 
our  faces?  For  the  atmosphere  round  and  next  to 
our  bodies,  having  imbibed  as  much  of  the  perspired 
vapor  as  it  can  well  contain,  receives  no  more,  and 
the  evaporation  is  therefore  checked  and  retarded 


1758] 


Essays 


27 


till  we  drive  away  that  atmosphere,  and  bring  drier 
air  in  its  place,  that  will  receive  the  vapor,  and 
thereby  facilitate  and  increase  the  evaporation.  Cer- 
tain it  is  that  mere  blowing  of  air  on  a  dry  body  does 
not  cool  it,  as  any  one  may  satisfy  himself  by  blowing 
with  a  bellows  on  the  dry  ball  of  a  thermometer;  the 
mercury  will  not  fall;  if  it  moves  at  all,  it  rather 
rises,  as  being  warmed  by  the  friction  of  the  air  on 
its  surface. 

To  these  queries  of  imagination  I  will  only  add 
one  practical  observation, — that  wherever  it  is 
thought  proper  to  give  ease  in  cases  of  painful  in- 
flammation in  the  flesh  (as  from  burnings  or  the 
like)  by  cooling  the  part,  linen  cloths  wet  with  spirit 
and  applied  to  the  part  inflamed,  will  produce  the 
coolness  required,  better  than  if  wet  with  water,  and 
will  continue  it  longer.  For  water,  though  cold 
when  first  applied,  will  soon  acquire  warmth  from 
the  flesh,  as  it  does  not  evaporate  fast  enough;  but 
the  cloths  wet  with  spirit  will  continue  cold  as  long 
as  any  spirit  is  left  to  keep  up  the  evaporation,  the 
parts  warmed  escaping  as  soon  as  they  are  warmed, 
and  carrying  off  the  heat  with  them.    I  am,  Sir,  &c, 

B.  Franklin. 


VI 


TO  OLIVER  NEAVE 

[No  date.] 

Dear  Sir: — I  cannot  be  of  opinion  with  you  that 
it  is  too  late  in  life  for  you  to  learn  to  swim.  The 
river  near  the  bottom  of  your  garden  affords  a  most 
convenient  place  for  the  purpose.  And  as  your  new 
employment  requires  your  being  often  on  the  water, 
of  which  you  have  such  a  dread,  I  think  you  would 
do  well  to  make  the  trial ;  nothing  being  so  likely  to 
remove  those  apprehensions  as  the  consciousness  of 
an  ability  to  swim  to  the  shore,  in  case  of  an  accident, 
or  of  supporting  yourself  in  the  water  till  a  boat 
could  come  to  take  you  up. 

I  do  not  know  how  far  corks  or  bladders  may  be 
useful  in  learning  to  swim,  having  never  seen  much 
trial  of  them.  Possibly  they  may  be  of  service  in 
supporting  the  body  while  you  are  learning  what  is 
called  the  stroke,  or  that  manner  of  drawing  in  and 
striking  out  the  hands  and  feet  that  is  necessary  to 
produce  progressive  motion.  But  you  will  be  no 
swimmer  till  you  can  place  some  confidence  in  the 
power  of  the  water  to  support  you;  I  would  there- 
28 


i768] 


Essays 


29 


fore  advise  the  acquiring  of  that  confidence  in  the 
first  place ;  especially  as  I  have  known  several  who, 
by  a  little  of  the  practice  necessary  for  that  purpose, 
have  insensibly  acquired  the  stroke,  taught  as  it  were 
by  nature. 

The  practice  I  mean  is  this:  Choosing  a  place 
where  the  water  deepens  gradually,  walk  coolly  into  it 
till  it  is  up  to  your  breast,  then  turn  round,  your  face 
to  the  shore,  and  throw  an  egg  into  the  water  between 
you  and  the  shore.  It  will  sink  to  the  bottom,  and  be 
easily  seen  there,  as  your  water  is  clear.  It  must  lie 
in  water  so  deep  as  that  you  cannot  reach  it  to  take 
it  up  but  by  diving  for  it.  To  encourage  yourself  in 
order  to  do  this,  reflect  that  your  progress  will  be 
from  deeper  to  shallower  water,  and  that  at  any  time 
you  may,  by  bringing  your  legs  under  you  and  stand- 
ing on  the  bottom,  raise  your  head  far  above  the 
water.  Then  plunge  under  it  with  your  eyes  open, 
throwing  yourself  towards  the  egg,  and  endeavouring 
by  the  action  of  your  hands  and  feet  against  the  water 
to  get  forward  till  within  reach  of  it.  In  this  attempt 
you  will  find  that  the  water  buoys  you  up  against 
your  inclination;  that  it  is  not  so  easy  a  thing  to  sink 
as  you  imagined;  that  you  cannot  but  by  active 
force  get  down  to  the  egg.  Thus  you  feel  the  power 
of  the  water  to  support  you,  and  learn  to  confide 
in  that  power;  while  your  endeavours  to  overcome 
it,  and  to  reach  the  egg,  teach  you  the  manner  of 
acting  on  the  water  with  your  feet  and  hands,  which 
action  is  afterwards  used  in  swimming  to  support 
your  head  higher  above  water,  or  to  go  forward 
through  it. 


3o 


Benjamin  Franklin 


[1768 


I  would  the  more  earnestly  press  you  to  the  trial 
of  this  method,  because,  though  I  think  I  satisfied 
you  that  your  body  is  lighter  than  water,  and  that 
you  might  float  in  it  a  long  time  with  your  mouth 
free  for  breathing,  if  you  would  put  yourself  in  a 
proper  posture,  and  would  be  still  and  forbear  strug- 
gling; yet  till  you  have  obtained  this  experimental 
confidence  in  the  water,  I  cannot  depend  on  your  hav- 
ing the  necessary  presence  of  mind  to  recollect  that 
posture  and  the  directions  I  gave  you  relating  to 
it.  The  surprise  may  put  all  out  of  your  mind.  For 
though  we  value  ourselves  on  being  reasonable, 
knowing  creatures,  reason  and  knowledge  seem  on 
such  occasions  to  be  of  little  use  to  us;  and  the 
brutes,  to  whom  we  allow  scarce  a  glimmering  of 
either,  appear  to  have  the  advantage  of  us. 

I  will,  however,  take  this  opportunity  of  repeating 
those  particulars  to  you  which  I  mentioned  in  our 
last  conversation,  as,  by  perusing  them  at  your 
leisure,  you  may  possibly  imprint  them  so  in  your 
memory  as  on  occasion  to  be  of  some  use  to  you. 

1.  That  though  the  legs,  arms,  and  head  of  a 
human  body,  being  solid  parts,  are  specifically  some- 
thing heavier  than  fresh  water,  yet  the  trunk,  partic- 
ularly the  upper  part,  from  its  hollowness,  is  so  much 
lighter  than  water,  as  that  the  whole  of  the  body 
taken  together  is  too  light  to  sink  wholly  under 
water,  but  some  part  will  remain  above,  until  the 
lungs  become  filled  with  water,  which  happens  from 
drawing  water  into  them  instead  of  air,  when  a  per- 
son in  the  fright  attempts  breathing  while  the  mouth 
and  nostrils  are  under  water. 


1768] 


Essays 


31 


2.  That  the  legs  and  arms  are  specifically  lighter 
than  salt  water,  and  will  be  supported  by  it,  so  that  a 
human  body  would  not  sink  in  salt  water,  though  the 
lungs  were  filled  as  above,  but  from  the  greater 
specific  gravity  of  the  head. 

3.  That  therefore  a  person  throwing  himself  on  his 
back  in  salt  water,  and  extending  his  arms,  may  easily 
lie  so  as  to  keep  his  mouth  and  nostrils  free  for 
breathing;  and  by  a  small  motion  of  his  hands  may 
prevent  turning,  if  he  should  perceive  any  tendency 
to  it. 

4.  That  in  fresh  water,  if  a  man  throws  himself  on 
his  back,  near  the  surface,  he  cannot  long  continue  in 
that  situation  but  by  proper  action  of  his  hands  on 
the  water.  If  he  uses  no  such  action,  the  legs  and 
lower  part  of  the  body  will  gradually  sink  till  he 
comes  into  an  upright  position,  in  which  he  will  con- 
tinue suspended,  the  hollow  of  the  breast  keeping  the 
head  uppermost. 

5.  But  if,  in  this  erect  position,  the  head  is  kept 
upright  above  the  shoulders,  as  when  we  stand  on  the 
ground,  the  immersion  will,  by  the  weight  of  that 
part  of  the  head  that  is  out  of  water,  reach  above  the 
mouth  and  nostrils,  perhaps  a  little  above  the  eyes, 
so  that  a  man  cannot  long  remain  suspended  in  water 
with  his  head  in  that  position. 

6.  The  body  continuing  suspended  as  before,  and 
upright,  if  the  head  be  leaned  quite  back,  so  that  the 
face  looks  upwards,  all  the  back  part  of  the  head  be- 
ing then  under  water,  and  its  weight  consequently  in 
a  great  measure  supported  by  it,  the  face  will  remain 
above  water  quite  free  for  breathing,  will  rise  an  inch 


32 


Benjamin  Franklin 


higher  every  inspiration,  and  sink  as  much  every  ex- 
piration, but  never  so  low  as  that  the  water  may  come 
over  the  mouth. 

7.  If  therefore  a  person  unacquainted  with  swim- 
ming and  falling  accidentally  into  the  water,  could 
have  presence  of  mind  sufficient  to  avoid  struggling 
and  plunging,  and  to  let  the  body  take  this  natural 
position,  he  might  continue  long  safe  from  drowning 
till  perhaps  help  would  come.  For  as  to  the  clothes, 
their  additional  weight  while  immersed  is  very  incon- 
siderable, the  water  supporting  it,  though  when  he 
comes  out  of  the  water  he  would  find  them  very 
heavy  indeed. 

But,  as  I  said  before,  I  would  not  advise  you  or 
any  one  to  depend  on  having  this  presence  of  mind 
on  such  an  occasion,  but  learn  firmly  to  swim;  as  I 
wish  all  men  were  taught  to  do  in  their  youth.  They 
would,  on  many  occurrences,  be  the  safer  for  having 
that  skill,  and  on  many  more  the  happier,  as  freer 
from  painful  apprehensions  of  danger,  to  say  nothing 
of  the  enjoyment  in  so  delightful  and  wholesome  an 
exercise.  Soldiers  particularly  should,  methinks,  all 
be  taught  to  swim ;  it  might  be  of  frequent  use  either 
in  surprising  an  enemy,  or  saving  themselves.  And 
if  I  had  now  boys  to  educate,  I  should  prefer  those 
schools  (other  things  being  equal)  where  an  oppor- 
tunity was  offered  for  acquiring  so  advantageous  an 
art,  which,  once  learned,  is  never  forgotten. 

I  am,  Sir,  &c, 

B.  Franklin. 


VII 


TO  M.  DUBOURG* 

I  am  apprehensive  that  I  shall  not  be  able  to  find 
leisure  for  making  all  the  disquisitions  and  experi- 
ments which  would  be  desirable  on  this  subject.  I 
must,  therefore,  content  myself  with  a  few  remarks. 

The  specific  gravity  of  some  human  bodies,  in 
comparison  to  that  of  water,  has  been  examined 
by  Mr.  Robinson,  in  our  Philosophical  Transactions, 
Volume  L.,  page  30,  for  the  year  1757.  He  asserts 
that  fat  persons  with  small  bones  float  most  easily 
upon  the  water. 

The  diving-bell  is  accurately  described  in  our 
Transactions. 

When  I  was  a  boy  I  made  two  oval  palettes,  each 
about  ten  inches  long  and  six  broad,  with  a  hole  for 
the  thumb,  in  order  to  retain  it  fast  in  the  palm  of 
my  hand.  They  much  resembled  a  painter's  palettes. 
In  swimming  I  pushed  the  edges  of  these  forward, 
and  I  struck  the  water  with  their  flat  surfaces  as  I 
drew  them  back.  I  remember  I  swam  faster  by 
means  of  these  palettes,  but  they  fatigued  my  wrists. 
I  also  fitted  to  the  soles  of  my  feet  a  kind  of  sandals ; 

1  Translated  from  Dubourg's  edition  of  Franklin's  Works,  vol.  ii.,  p. 
258. 

33 


34 


Benjamin  Franklin 


[1768 


but  I  was  not  satisfied  with  them,  because  I  observed 
that  the  stroke  is  partly  given  by  the  inside  of  the 
feet  and  the  ankles,  and  not  entirely  with  the  soles  of 
the  feet. 

We  have  here  waistcoats  for  swimming,  which  are 
made  of  double  sail-cloth,  with  small  pieces  of  cork 
quilted  in  between  them. 

I  know  nothing  of  the  scaphandre  of  M.  de  la 
Chapelle. 

I  know  by  experience  that  it  is  a  great  comfort  to  a 
swimmer  who  has  a  considerable  distance  to  go,  to 
turn  himself  sometimes  on  his  back,  and  to  vary  in 
other  respects  the  means  of  procuring  a  progressive 
motion. 

When  he  is  seized  with  the  cramp  in  the  leg,  the 
method  of  driving  it  away  is,  to  give  to  the  parts 
affected  a  sudden,  vigorous,  and  violent  shock;  which 
he  may  do  in  the  air  as  he  swims  on  his  back. 

During  the  great  heats  of  summer  there  is  no 
danger  in  bathing,  however  warm  we  may  be,  in 
rivers  which  have  been  thoroughly  warmed  by  the 
sun.  But  to  throw  one's  self  into  cold  spring  water, 
when  the  body  has  been  heated  by  exercise  in  the 
sun,  is  an  imprudence  which  may  prove  fatal.  I 
once  knew  an  instance  of  four  young  men  who,  hav- 
ing worked  at  harvest  in  the  heat  of  the  day,  with  a 
view  of  refreshing  themselves  plunged  into  a  spring  of 
cold  water ;  two  died  upon  the  spot,  a  third  the  next 
morning,  and  the  fourth  recovered  with  great  diffi- 
culty. A  copious  draught  of  cold  water,  in  similar 
circumstances,  is  frequently  attended  with  the  same 
effect  in  North  America. 


l768] 


Essays 


35 


The  exercise  of  swimming  is  one  of  the  most 
healthy  and  agreeable  in  the  world.  After  having 
swam  for  an  hour  or  two  in  the  evening,  one  sleeps 
coolly  the  whole  night,  even  during  the  most  ardent 
heat  of  summer.  Perhaps,  the  pores  being  cleansed, 
the  insensible  perspiration  increases  and  occasions 
this  coolness.  It  is  certain  that  much  swimming  is 
the  means  of  stopping  a  diarrhoea,  and  even  of  pro- 
ducing a  constipation.  With  respect  to  those  who 
do  not  know  how  to  swim,  or  who  are  affected  with 
a  diarrhoea  at  a  season  which  does  not  permit  them 
to  use  that  exercise,  a  warm  bath,  by  cleansing  and 
purifying  the  skin,  is  found  very  salutary,  and  often 
effects  a  radical  cure.  I  speak  from  my  own  experi- 
ence, frequently  repeated,  and  that  of  others,  to 
whom  I  have  recommended  this. 

You  will  not  be  displeased  if  I  conclude  these  hasty 
remarks  by  informing  you  that  as  the  ordinary 
method  of  swimming  is  reduced  to  the  act  of  rowing 
with  the  arms  and  legs,  and  is  consequently  a  labori- 
ous and  fatiguing  operation  when  the  space  of  water 
to  be  crossed  is  considerable,  there  is  a  method  in 
which  a  swimmer  may  pass  to  a  great  distance  with 
much  facility,  by  means  of  a  sail.  This  discovery  I 
fortunately  made  by  accident,  and  in  the  following 
manner: 

When  I  was  a  boy  I  amused  myself  one  day  with 
flying  a  paper  kite;  and  approaching  the  bank  of  a 
pond,  which  was  near  a  mile  broad,  I  tied  the  string 
to  a  stake  and  the  kite  ascended  to  a  very  considera- 
ble height  above  the  pond  while  I  was  swimming.  In 
a  little  time,  being  desirous  of  amusing  myself  with 


36 


Benjamin  Franklin 


[1768 


my  kite,  and  enjoying  at  the  same  time  the  pleasure 
of  swimming,  I  returned,  and  loosing  from  the  stake 
the  string  with  the  little  stick  which  was  fastened  to 
it,  went  again  into  the  water,  where  I  found  that, 
lying  on  my  back  and  holding  the  stick  in  my  hands, 
I  was  drawn  along  the  surface  of  the  water  in  a  very 
agreeable  manner.  Having  then  engaged  another 
boy  to  carry  my  clothes  round  the  pond,  to  a  place 
which  I  pointed  out  to  him  on  the  other  side,  I  be- 
gan to  cross  the  pond  with  my  kite,  which  carried  me 
quite  over  without  the  least  fatigue,  and  with  the 
greatest  pleasure  imaginable.  I  was  only  obliged 
occasionally  to  halt  a  little  in  my  course  and  resist  its 
progress  when  it  appeared  that,  by  following  too 
quick,  I  lowered  the  kite  too  much ;  by  doing  which 
occasionally  I  made  it  rise  again.  I  have  never  since 
that  time  practised  this  singular  mode  of  swimming, 
though  I  think  it  not  impossible  to  cross  in  this  man- 
ner from  Dover  to  Calais.  The  packet-boat,  how- 
ever, is  still  preferable.  B.  Franklin. 


VIII 


TO  M.  DUBOURG.1 

London,  28  July,  1768. 

I  greatly  approve  the  epithet  which  you  give,  in 
your  letter  of  the  8th  of  June,  to  the  new  method  of 
treating  the  small-pox,  which  you  call  the  tonic  or 
bracing  method;  I  will  take  occasion  from  it  to  men- 
tion a  practice  to  which  I  have  accustomed  myself. 
You  know  the  cold  bath  has  long  been  in  vogue  here 
as  a  tonic;  but  the  shock  of  the  cold  water  has 
always  appeared  to  me,  generally  speaking,  as  too 
violent,  and  I  have  found  it  much  more  agreeable  to 
my  constitution  to  bathe  in  another  element,  I  mean 
cold  air.  With  this  view  I  rise  almost  every  morning 
and  sit  in  my  chamber  without  any  clothes  whatever, 
half  an  hour  or  an  hour,  according  to  the  season, 
either  reading  or  writing.  This  practice  is  not  in  the 
least  painful,  but,  on  the  contrary,  agreeable ;  and,  if 
I  return  to  bed  afterwards,  before  I  dress  myself,  as 
sometimes  happens,  I  make  a  supplement  to  my 
night's  rest  of  one  or  two  hours  of  the  most  pleasing 
sleep  that  can  be  imagined.  I  find  no  ill  conse- 
quences whatever  resulting  from  it,  and  that  at  least 
it  does  not  injure  my  health,  if  it  does  not  in  fact  con- 
tribute much  to  its  perservation.  I  shall  therefore 
call  it  for  the  future  a  bracing  or  tonic  bath. 

B.  Franklin. 

1  Translated  from  M.  Dubourg's  edition  of  Franklin's  Works,  vol. 
ii.,  p.  310- 

37 

103215 


TO  M.  DUBOURG 

London,  io  March,  1773. 

Sir: — As  to  the  magnetism  which  seems  produced 
by  electricity,  my  real  opinion  is  that  these  two 
powers  of  nature  have  no  affinity  with  each  other, 
and  that  the  apparent  production  of  magnetism  is 
purely  accidental.  The  matter  may  be  explained 
thus: 

1  st.    The  earth  is  a  great  magnet. 

2dly.  There  is  a  subtile  fluid,  called  the  magnetic 
fluid,  which  exists  in  all  ferruginous  bodies,  equally 
attracted  by  all  their  parts,  and  equally  diffused 
through  their  whole  substance;  at  least  where  the 
equilibrium  is  not  disturbed  by  a  power  superior  to 
the  attraction  of  the  iron. 

3dly.  This  natural  quantity  of  the  magnetic 
fluid,  which  is  contained  in  a  given  piece  of  iron, 
may  be  put  in  motion  so  as  to  be  more  rarefied  in  one 
part  and  more  condensed  in  another;  but  it  cannot 
be  withdrawn  by  any  force  that  we  are  yet  made 
acquainted  with,  so  as  to  leave  the  whole  in  a  nega- 
tive state,  at  least  relatively  to  its  natural  quantity; 
neither  can  it  be  introduced  so  as  to  put  the  iron 
into  a  positive  state,  or  render  it  plus.  In  this 
respect,  therefore,  magnetism  differs  from  electricity. 
38 


1773] 


Essays 


39 


4thly.  A  piece  of  soft  iron  allows  the  magnetic 
fluid  which  it  contains  to  be  put  in  motion  by  a 
moderate  force;  so  that,  being  placed  in  a  line  with 
the  magnetic  pole  of  the  earth,  it  immediately  ac- 
quires the  properties  of  a  magnet,  its  magnetic  fluid 
being  drawn  or  forced  from  one  extremity  to  the 
other;  and  this  effect  continues  as  long  as  it  remains 
in  the  same  position,  one  of  its  extremities  becoming 
positively  magnetized,  and  the  other  negatively. 
This  temporary  magnetism  ceases  as  soon  as  the 
iron  is  turned  east  and  west,  the  fluid  immediately 
diffusing  itself  equally  through  the  whole  iron,  as  in 
its  natural  state. 

5thly.  The  magnetic  fluid  in  hard  iron,  or  steel, 
is  put  in  motion  with  more  difficulty,  requiring  a 
force  greater  than  the  earth  to  excite  it;  and,  when 
once  it  has  been  forced  from  one  extremity  of  the 
steel  to  the  other,  it  is  not  easy  for  it  to  return; 
and  thus  a  bar  of  steel  is  converted  into  a  perma- 
nent magnet. 

6thly.  A  great  heat  by  expanding  the  substance 
of  this  steel  and  increasing  the  distance  between  its 
particles,  affords  a  passage  to  the  magnetic  fluid, 
which  is  thus  again  restored  to  its  proper  equilib- 
rium; the  bar  appearing  no  longer  to  possess  mag- 
netic virtue. 

7thly.  A  bar  of  steel,  which  is  not  magnetic, 
being  placed  in  the  same  position,  relatively  to  the 
pole  of  the  earth,  which  the  magnetic  needle  as- 
sumes, and  in  this  position  being  heated  and  sud- 
denly cooled,  becomes  a  permanent  magnet.  The 
reason  is,  that  while  the  bar  was  hot,  the  magnetic 


4o 


Benjamin  Franklin 


[1773 


fluid  which  it  naturally  contained  was  easily  forced 
from  one  extremity  to  the  other  by  the  magnetic 
virtue  of  the  earth ;  and  that  the  hardness  and  con- 
densation, produced  by  the  sudden  cooling  of  the 
bar,  retained  it  in  this  state  without  permitting  it 
to  resume  its  original  situation. 

8thly.  The  violent  vibrations  of  the  particles  of  a 
steel  bar,  when  forcibly  struck  in  the  same  position, 
separate  the  particles  in  such  a  manner  during  their 
vibration,  that  they  permit  a  portion  of  the  mag- 
netic fluid  to  pass,  influenced  by  the  natural  magnet- 
ism of  the  earth;  and  it  is  afterwards  so  forcibly 
retained  by  the  reapproach  of  the  particles,  when 
the  vibration  ceases,  that  the  bar  becomes  a  perma- 
nent magnet. 

c-thly.  An  electric  shock  passing  through  a  needle 
in  a  like  position,  and  dilating  it  for  an  instant,  ren- 
ders it,  for  the  same  reason,  a  permanent  magnet; 
that  is,  not  by  imparting  magnetism  to  it,  but  by 
allowing  its  proper  magnetic  fluid  to  put  itself  in 
motion. 

iothly.  Thus  there  is  not  in  reality  more  mag- 
netism in  a  given  piece  of  steel  after  it  is  become 
magnetic,  than  existed  in  it  before.  The  natural 
quantity  is  only  displaced  or  repelled.  Hence  it 
follows,  that  a  strong  apparatus  of  magnets  may 
charge  millions  of  bars  of  steel,  without  communi- 
cating to  them  any  part  of  its  proper  magnetism; 
only  putting  in  motion  the  magnetism  which  already 
existed  in  these  bars. 

I  am  chiefly  indebted  to  that  excellent  philo- 
sopher of  Petersburg,  Mr.  ^pinus,  for  this  hypo- 


1773] 


Essays 


41 


thesis,  which  appears  to  me  equally  ingenious  and 
solid.  I  say  chiefly,  because,  as  it  is  many  years 
since  I  read  his  book,  which  I  have  left  in  America, 
it  may  happen  that  I  may  have  added  to  or  altered 
it  in  some  respect;  and  if  I  have  misrepresented 
any  thing,  the  error  ought  to  be  charged  to  my 
account. 

If  this  hypothesis  appears  admissible,  it  will  serve 
as  an  answer  to  the  greater  part  of  your  questions. 
I  have  only  one  remark  to  add,  which  is,  that  how- 
ever great  the  force  is  of  magnetism  employed,  you 
can  only  convert  a  given  portion  of  steel  into  a 
magnet  of  a  force  proportioned  to  its  capacity  of 
retaining  its  magnetic  fluid  in  the  new  position  in 
which  it  is  placed,  without  letting  it  return.  Now 
this  power  is  different  in  different  kinds  of  steel,  but 
Hmited  in  all  kinds  whatever. 

B.  Franklin. 


X 


FROM  M.  DUBOURG 

Paris,  25  March,  1773. 

Sir: — If  I  have  rightly  understood  your  principles, 
the  glass  to  be  used  in  the  Leyden  experiment  ought 
to  combine  these  two  qualities:  first,  it  should  be 
impermeable  to  the  electric  fluid ;  secondly,  it  should 
not  be  impermeable  to  the  action  of  this  fluid;  or,  to 
express  the  same  thing  in  other  words,  the  electric 
fluid  must  not  be  able  to  pass  from  one  surface  to 
the  other,  but  its  afflux  on  one  of  the  surfaces  of 
the  glass  must  have  the  power  to  excite  an  efflux 
on  the  opposite  surface. 

Glass  generally  unites  these  two  qualities,  but  not 
every  kind  of  glass.  There  is  even  glass  that  the 
electric  fluid  passes  through  almost  as  readily  as  it 
enters  metals.  This  is  a  property  natural  to  some 
kinds  of  glass,  and  accidental  to  others.  It  would 
seem  astonishing  that  no  philosopher  had  yet  thought 
of  seeking  out  the  causes  of  all  these  differences,  if 
natural  philosophy  alone  were  equal  to  the  task; 
but  there  is  need  of  the  aid  of  chemistry,  which  cer- 
tainly may  throw  some  light  on  so  interesting  a 
subject. 

42 


1773] 


Essays 


43 


I  would  not  propose  to  the  chemists  to  analyze 
the  different  kinds  of  glass,  permeable  or  imperme- 
able to  electricity ;  but  to  endeavor  to  imitate  them, 
which  would  be  much  easier  for  them  to  do. 

Pure  vitrifiable  earth  is  without  doubt  the  only 
ingredient  in  rock  crystal,  which  may  be  considered 
as  a  true  natural  glass ;  but  art  has  not  yet  succeeded 
in  obtaining  for  us  a  glass  so  pure,  and  there  is  even 
very  little  reason  to  hope  that  such  perfection  can 
ever  be  attained. 

There  is  no  earth  known  so  vitrifiable  as  not  to 
require  some  auxiliary  solvent  to  facilitate  its  vitri- 
fication. Now  solvents  are  distinguished  into  three 
principal  kinds — which  are,  saline  solvents,  metallic 
solvents,  and  earthly  solvents ;  for  there  are  different 
kinds  of  earths,  which,  although  each  singly  is  re- 
fractory, yet  serve  as  mutual  solvents,  as  there  are 
also  many  kinds  of  salts,  and  many  kinds  of  metals, 
which  may  be  used  as  solvents  for  the  vitrifiable 
earths,  and  which  may  be  combined  in  different  pro- 
portions with  the  same  earths.  We  ought  not  to 
be  more  surprised  to  find  glass  more  or  less  perme- 
able to  electricity,  than  to  find  it  pervious  and  im- 
pervious to  light.  Since  there  is  transparent  glass 
and  opaque  glass,  or  glass  of  various  colors,  why 
should  there  not  be  glass  which  is  a  conductor,  and 
that  which  is  a  non-conductor,  of  electricity? 

It  would  not  be  a  problem  of  difficult  solution  for  a 
chemist,  but  yet  it  would  be  a  labor  requiring  consid- 
erable time,  to  furnish  us  with  a  comparative  table 
of  the  diffierent  kinds  of  glass  possessing  either  of 
these  qualities  in  all  their  various  degrees.  The 


44  Benjamin  Franklin  [1773 

places  merely,  occupied  by  your  greenish  American 
glass,  as  well  as  by  the  white  London  glass,  would  in- 
dicate at  the  first  glance  the  mixture  of  ingredients  of 
which  they  are  respectively  composed. 

On  the  other  hand,  as  the  intensity  of  heat  to 
which  the  substance  of  the  glass  is  exposed,  whether 
in  melting  or  annealing,  may  cause  the  evaporation 
of  some  of  these  ingredients,  and  as  this  heat  is  not 
equally  powerful  in  every  part  of  the  furnace,  it  is  not 
very  surprising  that  you  should  have  found  con- 
siderable difference  between  several  glass  globes 
from  the  same  manufactory,  as  you  inform  us. 

Independently  of  the  natural  properties  of  one 
kind  of  glass  or  another,  arising  from  their  particular 
composition,  great  differences  may  also  result  from 
the  different  thicknesses  of  their  masses,  were  it  from 
this  consideration  alone  that  the  heat  could  not  be 
precisely  the  same,  nor  the  rapidity  of  cooling  very 
nearly  equal,  in  the  different  layers  of  very  thick 
glass ;  without  taking  into  the  account  that  it  seems 
almost  impossible  that  the  action  of  the  electric  fluid 
in  motion  should  be  effectually  conveyed  from  one 
surface  to  another  of  a  very  massive  body. 

Lastly;  it  is  equally  easy  to  conceive  that  a  con- 
siderable degree  of  heat,  by  rarefying  the  substance 
of  thin  glass,  should  open  its  pores  to  the  electric  fluid; 
but  that  the  degree  of  heat  must  be  in  proportion  to 
the  thickness  of  the  glass;  and  that  Mr.  Kinnersley 
found  a  heat  of  only  two  hundred  and  ten  degrees 
(the  point  at  which  water  boils,  according  to  Fahren- 
heit's thermometer),  necessary  to  render  the  very 
thin  glass  of  a  Florence  flask  permeable  to  the  electric 


i773i  Essays  45 

shock,  while  Mr.  Cavendish  required  a  heat  of  four 
hundred  degrees  to  make  glass  a  little  thicker  per- 
meable to  the  common  stream. 

My  reason  for  wishing  that  some  chemist  would 
have  the  goodness  to  enlighten  us  upon  all  these 
points  is,  that  too  much  pains  cannot  be  taken  to 
spare  the  lovers  of  natural  philosophy  any  unneces- 
sary expense;  because  this  may  turn  some  entirely 
aside  from  its  pursuit,  and  somewhat  damp  the  zeal 
of  many  others.    I  am,  etc., 

M.  Dubourg. 


XI 


TO  M.  DUBOURG 

Your  observations  on  the  causes  of  death,  and  the 
experiments  which  you  propose  for  recalling  to  life 
those  who  appeared  to  be  killed  by  lightning,  demon- 
strate equally  your  sagacity  and  your  humanity. 
It  appears  that  the  doctrines  of  life  and  death  in 
general  are  yet  but  little  understood. 

A  toad  buried  in  sand  will  live,  it  is  said,  till  the 
sand  becomes  petrified,  and  then,  being  enclosed  in 
the  stone,  it  may  still  live  for  we  know  not  how  many 
ages.  The  facts  which  are  cited  in  support  of  this 
opinion  are  too  numerous  and  too  circumstantial  not 
to  deserve  a  certain  degree  of  credit.  As  we  are 
accustomed  to  see  all  the  animals  with  which  we  are 
acquainted  eat  and  drink,  it  appears  to  us  difficult  to 
conceive  how  a  toad  can  be  supported  in  such  a  dun- 
geon ;  but  if  we  reflect  that  the  necessity  of  nourish- 
ment which  animals  experience  in  their  ordinary  state 
proceeds  from  the  continual  waste  of  their  substance 
by  perspiration,  it  will  appear  less  incredible  that 
some  animals  in  a  torpid  state,  perspiring  less  be- 
cause they  use  no  exercise,  should  have  less  need  of 
46 


1773] 


Essays 


47 


aliment,  and  that  otners,  which  are  covered  with 
scales  or  shells,  which  stop  perspiration,  such  as  land 
and  sea  turtles,  serpents,  and  some  species  of  fish, 
should  be  able  to  subsist  a  considerable  time  with- 
out any  nourishment  whatever.  A  plant,  with  its 
flowers,  fades  and  dies  immediately  if  exposed  to  the 
air  without  having  its  root  immersed  in  a  humid  soil, 
from  which  it  may  draw  a  sufficient  quantity  of  moist- 
ure to  supply  that  which  exhales  from  its  substance 
and  is  carried  off  continually  by  the  air.  Perhaps, 
however,  if  it  were  buried  in  quicksilver  it  might  pre- 
serve for  a  considerable  space  of  time  its  vegetable 
life,  its  smell,  and  color.  If  this  be  the  case,  it  might 
prove  a  commodious  method  of  transporting  from  dis- 
tant countries  those  delicate  plants  which  are  unable 
to  sustain  the  inclemency  of  the  weather  at  sea,  and 
which  require  particular  care  and  attention.  I  have 
seen  an  instance  of  common  flies  preserved  in  a  man- 
ner somewhat  similar.  They  had  been  drowned  in 
Madeira  wine,  apparently  about  the  time  when  it  was 
bottled  in  Virginia  to  be  sent  hither  (to  London). 
At  the  opening  of  one  of  the  bottles  at  the  house  of 
a  friend  where  I  then  was  three  drowned  flies  fell  into 
the  first  glass  that  was  filled.  Having  heard  it  re- 
marked that  drowned  flies  were  capable  of  being  re- 
vived by  the  rays  of  the  sun,  I  proposed  making  the 
experiment  upon  these.  They  were,  therefore,  ex- 
posed to  the  sun  upon  a  sieve  which  had  been 
employed  to  strain  them  out  of  the  wine.  In  less 
than  three  hours  two  of  them  began  by  degrees  to 
recover  life.  They  commenced  by  some  convulsive 
motions  of  the  thighs,  and  at  length  they  raised 


48 


Benjamin  Franklin 


[1773 


themselves  upon  their  legs,  wiped  their  eyes  with  their 
forefeet,  beat  and  brushed  their  wings  with  their  hind 
feet,  and  soon  after  began  to  fly,  finding  themselves 
in  Old  England,  without  knowing  how  they  came 
thither.  The  third  continued  lifeless  till  sunset, 
when  losing  all  hopes  of  him,  he  was  thrown  away. 

I  wish  it  were  possible,  from  this  instance,  to  in- 
vent a  method  of  embalming  drowned  persons  in  such 
a  manner  that  they  may  be  recalled  to  life  at  any 
period,  however  distant ;  for  having  a  very  ardent  de- 
sire to  see  and  observe  the  state  of  America  a  hun- 
dred years  hence,  I  should  prefer  to  any  ordinary 
death  the  being  immersed  in  a  cask  of  Madeira  wine 
with  a  few  friends  till  that  time,  to  be  then  recalled 
to  life  by  the  solar  warmth  of  my  dear  country !  But 
since  in  all  probability  we  live  in  an  age  too  early  and 
too  near  the  infancy  of  science  to  hope  to  see  such  an 
art  brought  in  our  time  to  its  perfection,  I  must  for 
the  present  content  myself  with  the  treat  which  you 
are  so  kind  as  to  promise  me  of  the  resurrection  of  a 
fowl  or  a  turkey-cock. 

I  am,  etc., 

B.  Franklin. 


XII 


TO  DR.  BROWNRIGG 

London,  7  November,  1773. 

Dear  Sir: — I  thank  you  for  the  remarks  of  your 
learned  friend  at  Carlisle.  I  had,  when  a  youth, 
read  and  smiled  at  Pliny's  account  of  a  practice 
among  the  seamen  of  his  time,  to  still  the  waves  in  a 
storm  by  pouring  oil  into  the  sea;  which  he  men- 
tions, as  well  as  the  use  made  of  oil  by  the  divers; 
but  the  stilling  a  tempest  by  throwing  vinegar  into 
the  air  had  escaped  me.  I  think  with  your  friend, 
that  it  has  been  of  late  too  much  the  mode  to  slight 
the  learning  of  the  ancients.  The  learned,  too,  are 
apt  to  slight  too  much  the  knowledge  of  the  vulgar. 
The  cooling  by  evaporation  was  long  an  instance 
of  the  latter.  The  art  of  smoothing  the  waves  by  oil 
is  an  instance  of  both. 

Perhaps  you  may  not  dislike  to  have  an  account 
of  all  I  have  heard,  and  learnt,  and  done  in  this  way. 
Take  it  if  you  please  as  follows : 

In  1757,  being  at  sea  in  a  fleet  of  ninety-six  sail 
bound  against  Louisbourg,  I  observed  the  wakes  of 
two  of  the  ships  to  be  remarkably  smooth,  while  all 
the  others  were  ruffled  by  the  wind,  which  blew  fresh. 
Being  puzzled  with  the  differing  appearance,  I  at  last 
49 


50 


Benjamin  Franklin 


[1773 


pointed  it  out  to  our  captain,  and  asked  him  the 
meaning  of  it.  "The  cooks,"  said  he,  "have,  I  sup- 
pose, been  just  emptying  their  greasy  water  through 
the  scuppers,  which  has  greased  the  sides  of  those 
ships  a  little."  And  this  answer  he  gave  me  with  an 
air  of  some  little  contempt,  as  to  a  person  ignorant  of 
what  everybody  else  knew.  In  my  own  mind  I  at 
first  slighted  his  solution,  though  I  was  not  able  to 
think  of  another;  but  recollecting  what  I  had  for- 
merly read  in  Pliny,  I  resolved  to  make  some  experi- 
ment of  the  effect  of  oil  on  water,  when  I  should  have 
opportunity. 

Afterwards  being  again  at  sea  in  1762,  I  first  ob- 
served the  wonderful  quietness  of  oil  on  agitated 
water  in  the  swinging  glass  lamp  I  made  to  hang  up 
in  the  cabin,  as  described  in  my  printed  papers. 
This  I  was  continually  looking  at  and  considering  as 
an  appearance  to  me  inexplicable.  An  old  sea  cap- 
tain, then  a  passenger  with  me,  thought  little  of  it, 
supposing  it  an  effect  of  the  same  kind  with  that 
of  oil  put  on  water  to  smooth  it,  which  he  said  was  a 
practice  of  the  Bermudians  when  they  would  strike 
fish,  which  they  could  not  see  if  the  surface  of  the 
water  was  ruffled  by  the  wind.  This  practice  I  had 
never  before  heard  of,  and  was  obliged  to  him  for  the 
information;  though  I  thought  him  mistaken  as  to 
the  sameness  of  the  experiment,  the  operations  being 
different  as  well  as  the  effects.  In  one  case  the  water 
is  smooth  till  the  oil  is  put  on,  and  then  becomes 
agitated.  In  the  other  it  is  agitated  before  the 
oil  is  applied,  and  then  becomes  smooth.  The 
same  gentleman  told  me,  he  had  heard  it  was  a 


773] 


Essays 


5i 


practice  with  the  fishermen  of  Lisbon  when  about 
to  return  into  the  river  (if  they  saw  before 
them  too  great  a  surf  upon  the  bar,  which  they 
apprehended  might  fill  their  boats  in  passing)  to 
empty  a  bottle  or  two  of  oil  into  the  sea,  which 
would  suppress  the  breakers  and  allow  them  to  pass 
safely.  A  confirmation  of  this  I  have  not  since  had 
an  opportunity  of  obtaining,  but  discoursing  of  it 
with  another  person  who  had  often  been  in  the  Medi- 
terranean, I  was  informed  that  the  divers  there,  who, 
when  under  water  in  their  business,  need  light,  which 
the  curling  of  the  surface  interrupts  by  the  refractions 
of  so  many  little  waves,  let  a  small  quantity  of  oil 
now  and  then  out  of  their  mouths,  which  rising  to 
the  surface  smooths  it,  and  permits  the  light  to  come 
down  to  them.  All  these  informations  I  at  times  re- 
volved in  my  mind,  and  wondered  to  find  no  mention 
of  them  in  our  books  of  experimental  philosophy. 

At  length  being  at  Clapham,  where  there  is,  on  the 
common,  a  large  pond,  which  I  observed  one  day  to 
be  very  rough  with  the  wind,  I  fetched  out  a  cruet  of 
oil,  and  dropped  a  little  of  it  on  the  water.  I  saw  it 
spread  itself  with  surprising  swiftness  upon  the  sur- 
face ;  but  the  effect  of  smoothing  the  waves  was  not 
produced;  for  I  had  applied  it  first  on  the  leeward 
side  of  the  pond,  where  the  waves  were  greatest ;  and 
the  wind  drove  my  oil  back  upon  the  shore.  I  then 
went  to  the  windward  side  where  they  began  to  form ; 
and  there  the  oil,  though  not  more  than  a  tea- 
spoonful,  produced  an  instant  calm  over  a  space  sev- 
eral yards  square,  which  spread  amazingly,  and 
extended  itself  gradually  till  it  reached  the  lee  side, 


52 


Benjamin  Franklin 


[1773 


making  all  that  quarter  of  the  pond,  perhaps  half  an 
acre,  as  smooth  as  a  looking-glass. 

After  this  I  contrived  to  take  with  me,  whenever  I 
went  into  the  country,  a  little  oil  in  the  upper  hollow 
joint  of  my  bamboo  cane,  with  which  I  might  repeat 
the  experiment  as  opportunity  should  offer,  and  I 
found  it  constantly  to  succeed. 

In  these  experiments,  one  circumstance  struck  me 
with  particular  surprise.  This  was  the  sudden,  wide, 
and  forcible  spreading  of  a  drop  of  oil  on  the  face  of 
the  water,  which  I  do  not  know  that  anybody  has 
hitherto  considered.  If  a  drop  of  oil  is  put  on  a 
highly  polished  marble  table,  or  on  a  looking  glass 
that  lies  horizontally,  the  drop  remains  in  its  place, 
spreading  very  little.  But,  when  put  on  water,  it 
spreads  instantly  many  feet  round,  becoming  so  thin 
as  to  produce  the  prismatic  colors,  for  a  considerable 
space,  and  beyond  them  so  much  thinner  as  to  be  in- 
visible, except  in  its  effect  of  smoothing  the  waves  at 
a  much  greater  distance.  It  seems  as  if  a  mutual 
repulsion  between  its  particles  took  place  as  soon  as 
it  touched  the  water,  and  a  repulsion  so  strong  as  to 
act  on  other  bodies  swimming  on  the  surface,  as 
straw,  leaves,  chips,  etc.,  forcing  them  to  recede  every 
way  from  the  drop,  as  from  a  centre,  leaving  a  large 
clear  space.  The  quantity  of  this  force,  and  the  dis- 
tance to  which  it  will  operate,  I  have  not  yet  ascer- 
tained ;  but  I  think  it  is  a  curious  inquiry,  and  I  wish 
to  understand  whence  it  arises. 

In  our  journey  to  the  north,  when  we  had  the 
pleasure  of  seeing  you  at  Ormathwaite,  we  visited  the 
celebrated  Mr.  Smeaton,  near  Leeds.    Being  about 


17731 


Essays 


53 


to  show  him  the  smoothing  experiment  on  a  little 
pond  near  his  house,  an  ingenious  pupil  of  his,  Mr. 
Jessop,  then  present,  told  us  of  an  odd  appearance  on 
that  pond  which  had  lately  occurred  to  him.  He  was 
about  to  clean  a  little  cup  in  which  he  kept  oil,  and 
he  threw  upon  the  water  some  flies  that  had  been 
drowned  in  the  oil.  These  flies  presently  began  to 
move,  and  turned  round  on  the  water  very  rapidly,  as 
if  they  were  vigorously  alive,  though  on  examination 
he  found  they  were  not  so.  I  immediately  concluded 
that  the  motion  was  occasioned  by  the  power  of  the 
repulsion  above  mentioned,  and  that  the  oil,  issuing 
gradually  from  the  spongy  body  of  the  fly,  continued 
the  motion.  He  found  some  more  flies  drowned  in 
oil,  with  which  the  experiment  was  repeated  before 
us.  To  show  that  it  was  not  any  effect  of  life 
recovered  by  the  flies,  I  imitated  it  by  little  bits  of 
oiled  chips  and  paper,  cut  in  the  form  of  a  comma,  of 
the  size  of  a  common  fly ;  when  the  stream  of  repel- 
ling particles  issuing  from  the  point  made  the  comma 
turn  round  the  contrary  way.  This  is  not  a  chamber 
experiment ;  for  it  cannot  be  well  repeated  in  a  bowl 
or  dish  of  water  on  a  table.  A  considerable  surface 
of  water  is  necessary  to  give  room  for  the  expansion 
of  a  small  quantity  of  oil.  In  a  dish  of  water,  if  the 
smallest  drop  of  oil  be  let  fall  in  the  middle,  the  whole 
surface  is  presently  covered  with  a  thin  greasy  film 
proceeding  from  the  drop;  but  as  soon  as  that  film 
has  reached  the  sides  of  the  dish,  no  more  will  issue 
from  the  drop,  but  it  remains  in  the  form  of  oil;  the 
sides  of  the  dish  putting  a  stop  to  its  dissipation  by 
prohibiting  the  farther  expansion  of  the  film. 


54 


Benjamin  Franklin 


[1773 


Our  friend  Sir  John  Pringle,  being  soon  after 
in  Scotland,  learned  there  that  those  employed  in 
the  herring  fishery  could  at  a  distance  see  where 
the  shoals  of  herrings  were,  by  the  smoothness  of  the 
water  over  them,  which  might  possibly  be  occasioned, 
he  thought,  by  some  oiliness  proceeding  from  their 
bodies. 

A  gentleman  from  Rhode  Island  told  me,  it  had 
been  remarked  that  the  harbor  of  Newport  was  ever 
smooth  while  any  whaling  vessels  were  in  it;  which 
probably  arose  from  hence,  that  the  blubber  which 
they  sometimes  bring  loose  in  the  hold,  or  the  leak- 
age of  their  barrels,  might  afford  some  oil  to  mix 
with  that  water,  which  from  time  to  time  they  pump 
out,  to  keep  their  vessel  free,  and  that  some  oil  might 
spread  over  the  surface  of  the  water  in  the  harbor, 
and  prevent  the  forming  of  any  waves. 

This  prevention  I  would  thus  endeavor  to  explain. 

There  seems  to  be  no  natural  repulsion  between 
water  and  air,  such  as  to  keep  them  from  coming  into 
contact  with  each  other.  Hence  we  find  a  quantity 
of  air  in  water ;  and  if  we  extract  it  by  means  of  the 
air-pump,  the  same  water  again  exposed  to  the  air 
will  soon  imbibe  an  equal  quantity. 

Therefore  air  in  motion,  which  is  wind,  in  passing 
over  the  smooth  surface  of  water,  may  rub,  as  it 
were,  upon  that  surface,  and  raise  it  into  wrinkles, 
which,  if  the  wind  continues,  are  the  elements  of 
future  waves. 

The  smallest  wave  once  raised  does  not  immedi- 
ately subside  and  leave  the  neighboring  water  quiet; 
but  in  subsiding  raises  nearly  as  much  of  the  water 


1773] 


Essays 


55 


next  to  it,  the  friction  of  the  parts  making  little  dif- 
ference. Thus  a  stone  dropped  into  a  pool  raises  first 
a  single  wave  round  itself ;  and  leaves  it  by  sinking 
to  the  bottom;  but  that  first  wave  subsiding  raises 
a  second,  the  second  a  third,  and  so  on  in  circles  to  a 
great  extent. 

A  small  power  continually  operating  will  produce 
a  great  action.  A  finger  applied  to  a  weighty  sus- 
pended bell  can  at  first  move  it  but  little ;  if  repeat- 
edly applied  though  with  no  greater  strength,  the 
motion  increases  till  the  bell  swings  to  its  utmost 
height,  and  with  a  force  that  cannot  be  resisted  by 
the  whole  strength  of  the  arm  and  body.  Thus  the 
small  first-raised  waves,  being  continually  acted  upon 
by  the  wind,  are,  though  the  wind  does  not  increase 
in  strength,  continually  increased  in  magnitude,  ris- 
ing higher,  and  extending  their  bases,  so  as  to  include 
a  vast  mass  of  water  in  each  wave,  which  in  its  mo- 
tion acts  with  great  violence. 

But  if  there  is  a  mutual  repulsion  between  the  par- 
ticles of  oil,  and  no  attraction  between  oil  and  water, 
oil  dropped  on  water  will  not  be  held  together  by 
adhesion  to  the  spot  whereon  it  falls;  it  will  not  be 
imbibed  by  the  water ;  it  will  be  at  liberty  to  expand 
itself;  and  it  will  spread  on  a  surface  that,  besides 
being  smooth  to  the  most  perfect  degree  of  polish, 
prevents,  perhaps  by  repelling  the  oil,  all  immediate 
contact,  keeping  it  at  a  minute  distance  from  itself; 
and  the  expansion  will  continue  till  the  mutual  re- 
pulsion between  the  particles  of  the  oil  is  weakened 
and  reduced  to  nothing  by  their  distance. 

Now  I  imagine  that  the  wind,  blowing  over  water 


56 


Benjamin  Franklin 


[1773 


thus  covered  with  a  film  of  oil,  cannot  easily  catch 
upon  it,  so  as  to  raise  the  first  wrinkles,  but  slides 
over  it  and  leaves  it  smooth  as  it  finds  it.  It  moves 
a  little  the  oil  indeed,  which  being  between  it  and  the 
water,  serves  it  to  slide  with,  and  prevents  friction, 
as  oil  does  between  those  parts  of  a  machine  that 
would  otherwise  rub  hard  together.  Hence  the  oil 
dropped  on  the  windward  side  of  a  pond  proceeds 
gradually  to  leeward,  as  may  be  seen  by  the  smooth- 
ness it  carries  with  it,  quite  to  the  opposite  side. 
For  the  wind  being  thus  prevented  from  raising  the 
first  wrinkles,  that  I  call  the  elements  of  waves,  can- 
not produce  waves,  which  are  to  be  made  by  con- 
tinually acting  upon,  and  enlarging  those  elements, 
and  thus  the  whole  pond  is  calmed. 

Totally  therefore  we  might  suppress  the  waves  in 
any  required  place,  if  we  could  come  at  the  windward 
place  where  they  take  their  rise.  This  in  the  ocean 
can  seldom  if  ever  be  done.  But  perhaps  something 
may  be  done  on  particular  occasions,  to  moderate  the 
violence  of  the  waves  when  we  are  in  the  midst  of 
them,  and  prevent  their  breaking  where  that  would 
be  inconvenient. 

For,  when  the  wind  blows  fresh,  there  are  con- 
tinually rising  on  the  back  of  every  great  wave  a  num- 
ber of  small  ones,  which  roughen  its  surface,  and  give 
the  wind  hold,  as  it  were,  to  push  it  with  greater  force. 
This  hold  is  diminished,  by  preventing  the  generation 
of  those  small  ones.  And  possibly  too  when  a  wave's 
surface  is  oiled,  the  wind  in  passing  over  it  may  rather 
in  some  degree  press  it  down,  and  contribute  to  pre- 
vent its  rising  again,  instead  of  promoting  it. 


1773] 


Essays 


57 


This,  as  mere  conjecture,  would  have  little  weight, 
if  the  apparent  effects  of  pouring  oil  into  the  midst  of 
waves  were  not  onsiderable,  and  as  yet  not  other- 
wise accounted  for. 

When  the  wind  blows  so  fresh,  as  that  the  waves 
are  not  sufficiently  quick  in  obeying  its  impulse,  their 
tops  being  thinner  and  lighter  are  pushed  forward, 
broken,  and  turned  over  in  a  white  foam.  Common 
waves  lift  a  vessel  without  entering  it;  but  these 
when  large  sometimes  break  above  and  pour  over  it, 
doing  great  damage. 

That  this  effect  might  in  any  degree  be  prevented, 
or  the  height  and  violence  of  waves  in  the  sea  moder- 
ated, we  had  no  certain  account;  Pliny's  authority 
for  the  practice  of  seamen  in  his  time  being  slighted. 
But  discoursing  lately  on  this  subject  with  his  Excel- 
lency Count  Bentinck,  of  Holland,  his  son  the  Hon- 
orable Captain  Bentinck,  and  the  learned  Professor 
Allemand,  (to  all  whom  I  showed  the  experiment  of 
smoothing  in  a  windy  day  the  large  piece  of  water  at 
the  head  of  the  Green  Park,)  a  letter  was  mentioned, 
which  had  been  received  by  the  Count  from  Batavia, 
relative  to  the  saving  of  a  Dutch  ship  in  a  storm  by 
pouring  oil  into  the  sea.  I  much  desired  to  see  that 
letter,  and  a  copy  of  it  was  promised  me,  which  I 
afterward  received. 


Extract  of  a  Letter  from  Mr.  Tengnagel  to  Count  Ben- 
tinck, dated  at  Batavia,  5  January,  1770 

Near  the  islands  Paul  and  Amsterdam,  we  met 
with  a  storm,  which  had  nothing  particular  in  it 


53 


Benjamin  Franklin 


[1773 


worthy  of  being  communicated  to  you,  except  that 
the  captain  found  himself  obliged  for  greater  safety 
in  wearing  the  ship,  to  pour  oil  into  the  sea,  to  pre- 
vent the  waves  breaking  over  her,  which  had  an  ex- 
cellent effect,  and  succeeded  in  preserving  us.  As 
he  poured  out  but  a  little  at  a  time,  the  East  India 
Company  owes  perhaps  its  ship  to  only  six  demi-ames 
of  oil-olive.  I  was  present  upon  deck  when  this  was 
done ;  and  I  should  not  have  mentioned  this  circum- 
stance to  you,  but  that  we  have  found  people  here  so 
prejudiced  against  the  experiment,  as  to  make  it 
necessary  for  the  officers  on  board  and  myself  to  give 
a  certificate  of  the  truth  on  this  head,  of  which  we 
made  no  difficulty. 


On  this  occasion  I  mentioned  to  Captain  Bentinck 
a  thought  which  had  occurred  to  me  in  reading  the 
voyages  of  our  late  circumnavigators,  particularly 
where  accounts  are  given  of  pleasant  and  fertile 
islands  which  they  much  desired  to  land  upon,  when 
sickness  made  it  more  necessary,  but  could  not  effect 
a  landing  through  a  violent  surf  breaking  on  the 
shore,  which  rendered  it  impracticable.  My  idea  was 
that  possibly  by  sailing  to  and  fro  at  some  distance 
from  such  lee-shore,  continually  pouring  oil  into  the 
sea,  the  waves  might  be  so  much  depressed  and  les- 
sened before  they  reached  the  shore,  as  to  abate  the 
height  and  violence  of  the  surf,  and  permit  a  landing, 
which,  in  such  circumstances,  was  a  point  of  sufficient 
importance  to  justify  the  expense  of  the  oil  that 
might  be  requisite  for  the  purpose.    That  gentleman, 


1773] 


Essays 


59 


who  is  ever  ready  to  promote  what  may  be  of  public 
utility,  though  his  own  ingenious  inventions  have  not 
always  met  with  the  countenance  they  merited,  was 
so  obliging  as  to  invite  me  to  Portsmouth,  where  an 
opportunity  would  probably  offer,  in  the  course  of  a 
few  days,  of  making  the  experiment  on  some  of  the 
shores  about  Spithead,  in  which  he  kindly  proposed 
to  accompany  me,  and  to  give  assistance  with  such 
boats  as  might  be  necessary.  Accordingly,  about 
the  middle  of  October  last,  I  went  with  some  friends 
to  Portsmouth,  and  a  day  of  wind  happening,  which 
made  a  lee-shore  between  Haslar  Hospital  and  the 
point  near  Jillkecker,  we  went  from  the  Centaur  with 
the  long-boat  and  barge  towards  that  shore.  Our 
disposition  was  this,  the  long-boat  was  anchored 
about  a  quarter  of  a  mile  from  the  shore ;  part  of  the 
company  were  landed  behind  the  point  (a  place  more 
sheltered  from  the  sea),  who  came  round  and  placed 
themselves  opposite  to  the  long-boat,  where  they 
might  observe  the  surf,  and  note  if  any  change 
occurred  in  it  upon  using  the  oil.  Another  party,  in 
the  barge,  plied  to  windward  of  the  long-boat,  as  far 
from  her  as  she  was  from  the  shore,  making  trips  of 
about  half  a  mile  each,  pouring  oil  continually  out  of 
a  large  stone  bottle,  through  a  hole  in  the  cork,  some- 
what bigger  than  a  goose-quill.  The  experiment  had 
not,  in  the  main  point,  the  success  we  wished,  for  no 
material  difference  was  observed  in  the  height  or 
force  of  the  surf  upon  the  shore;  but  those  who 
were  in  the  long-boat  could  observe  a  tract  of 
smoothed  water,  the  whole  of  the  distance  in  which 
the  barge  poured  the  oil,  and  gradually  spreading  in 


i 


6o  Benjamin  Franklin  [i773 


breadth  towards  the  long-boat.  I  call  it  smoothed, 
not  that  it  was  laid  level,  but  because,  though  the 
swell  continued,  its  surface  was  not  roughened  by  the 
wrinkles,  or  smaller  waves,  before  mentioned,  and 
none  or  very  few  white  caps  (or  waves  whose  tops 
turn  over  in  foam)  appeared  in  that  whole  space, 
though  to  windward  and  leeward  of  it  there  were 
plenty ;  and  a  wherry,  that  came  round  the  point  un- 
der sail,  in  her  way  to  Portsmouth,  seemed  to  turn 
into  that  tract  of  choice,  and  to  use  it  from  end  to 
end  as  a  piece  of  turnpike  road. 

It  may  be  of  use  to  relate  the  circumstances  of  an 
experiment  that  does  not  succeed,  since  they  may 
give  hints  of  amendment  in  future  trials ;  it  is  there- 
fore I  have  been  thus  particular.  I  shall  only  add 
what  I  apprehend  may  have  been  the  reason  of  our 
disappointment. 

I  conceive  that  the  operation  of  oil  on  water  is: 
first,  to  prevent  the  raising  of  new  waves  by  the 
wind ;  and,  secondly,  to  prevent  its  pushing  those  be- 
fore raised  with  such  force,  and  consequently  their 
continuance  of  the  same  repeated  height,  as  they 
would  have  done  if  their  surface  were  not  oiled.  But 
oil  will  not  prevent  waves  being  raised  by  another 
power — by  a  stone,  for  instance,  falling  into  a  still 
pond;  for  they  then  rise  by  the  mechanical  impulse 
of  the  stone,  which  the  greasiness  on  the  surrounding 
water  cannot  lessen  or  prevent,  as  it  can  prevent  the 
winds  catching  the  surface  and  raising  it  into  waves. 
Now  waves  once  raised,  whether  by  the  wind  or  any 
other  power,  have  the  same  mechanical  operation, 
by  which  they  continue  to  rise  and  fall,  as  a  pendulum 


1773] 


Essays 


61 


will  continue  to  swing  a  long  time  after  the  force 
ceases  to  act  by  which  the  motion  was  first  produced; 
that  motion  will,  however,  cease  in  time ;  but  time  is 
necessary.  Therefore,  though  oil  spread  on  an  agi- 
tated sea  may  weaken  the  push  of  the  wind  on  those 
waves  whose  surfaces  are  covered  by  it,  and  so,  by 
receiving  less  fresh  impulse,  they  may  gradually  sub- 
side ;  yet  a  considerable  time,  or  a  distance  through 
which  they  will  take  time  to  move,  may  be  necessary 
to  make  the  effect  sensible  on  any  shore  in  a  diminu- 
tion of  the  surf;  for  we  know  that,  when  wind 
ceases  suddenly,  the  waves  it  has  raised  do  not  as 
suddenly  subside,  but  settle  gradually,  and  are  not 
quite  down  till  after  the  wind  has  ceased.  So,  though 
we  should,  by  oiling  them,  take  off  the  effect  of  wind 
on  waves  already  raised,  it  is  not  to  be  expected  that 
those  waves  should  be  instantly  levelled.  The  mo- 
tion they  have  received  will,  for  some  time,  continue; 
and,  if  the  shore  is  not  far  distant,  they  arrive  there 
so  soon,  that  their  effect  upon  it  will  not  be  visibly 
diminished.  Possibly,  therefore,  if  we  had  begun 
our  operations  at  a  greater  distance,  the  effect  might 
have  been  more  sensible.  And  perhaps  we  did  not 
pour  oil  in  sufficient  quantity.  Future  experiments 
may  determine  this. 

I  was,  however,  greatly  obliged  to  Captain  Ben- 
tinck  for  the  cheerful  and  ready  aids  he  gave  me; 
and  I  ought  not  to  omit  mentioning  Mr.  Banks,  Dr. 
Solander,  General  Carnoc,  and  Dr.  Blagden,  who  all 
assisted  at  the  experiment,  during  that  blustering, 
unpleasant  day,  with  a  patience  and  activity  that 
could  only  be  inspired  by  a  zeal  for  the  improvement 


62 


Benjamin  Franklin 


[1773 


of  knowledge,  such  especially  as  might  possibly  be  of 
use  to  men  in  situations  of  distress. 

I  would  wish  you  to  communicate  this  to  your  in- 
genious friend,  Mr.  Farish,  with  my  respects;  and  be- 
lieve me  to  be,  with  sincere  esteem,  dear  sir, 
Your  most  obedient  humble  servant, 

B.  Franklin. 


XIII 


the  ephemera:  an  emblem  op  human  life 

TO  MADAME  BRILLON,   OF  PASSY 

You  may  remember,  my  dear  friend,  that  when 
we  lately  spent  that  happy  day  in  the  delightful 
garden  and  sweet  society  of  the  Moulin  Joly,  I  stop- 
ped a  little  in  one  of  our  walks,  and  stayed  some  time 
behind  the  company.  We  had  been  shown  number- 
less skeletons  of  a  kind  of  little  fly,  called  an  ephem- 
era, whose  successive  generations,  we  were  told,  were 
bred  and  expired  within  the  day.  I  happened  to  see 
a  living  company  of  them  on  a  leaf,  who  appeared 
to  be  engaged  in  conversation.  You  know  I  under- 
stand all  the  inferior  animal  tongues.  My  too  great 
application  to  the  study  of  them  is  the  best  excuse 
I  can  give  for  the  little  progress  I  have  made  in  your 
charming  language.  I  listened  through  curiosity  to 
the  discourse  of  these  little  creatures ;  but  as  they,  in 
their  national  vivacity,  spoke  three  or  four  together, 
I  could  make  but  little  of  their  conversation.  I 
found,  however,  by  some  broken  expressions  that 
I  heard  now  and  then,  they  were  disputing  warmly 
on  the  merit  of  two  foreign  musicians,  one  a  cousin, 
the  other  a  moscketo;  in  which  dispute  they  spent 

63 


64 


Benjamin  Franklin 


[1778 


their  time,  seemingly  as  regardless  of  the  shortness 
of  life  as  if  they  had  been  sure  of  living  a  month. 
Happy  people !  thought  I ;  you  are  certainly  under  a 
wise,  just,  and  mild  government,  since  you  have  no 
public  grievances  to  complain  of,  nor  any  subject 
of  contention  but  the  perfections  and  imperfections 
of  foreign  music.  I  turned  my  head  from  them  to 
an  old  gray-headed  one,  who  was  single  on  another 
leaf,  and  talking  to  himself.  Being  amused  with 
his  soliloquy,  I  put  it  down  in  writing,  in  hopes  it 
will  likewise  amuse  her  to  whom  I  am  so  much  in- 
debted for  the  most  pleasing  of  all  amusements, 
her  delicious  company  and  heavenly  harmony. 

"  It  was,"  said  he,  "  the  opinion  of  learned  philo- 
sophers of  our  race,  who  lived  and  flourished  long 
before  my  time,  that  this  vast  world,  the  Moulin 
Joly,  could  not  itself  subsist  more  than  eighteen 
hours;  and  I  think  there  was  some  foundation  for 
that  opinion,  since,  by  the  apparent  motion  of  the 
great  luminary  that  gives  life  to  all  nature,  and 
which  in  my  time  has  evidently  declined  consider- 
ably towards  the  ocean  at  the  end  of  our  earth,  it 
must  then  finish  its  course,  be  extinguished  in  the 
waters  that  surround  us,  and  leave  the  world  in  cold 
and  darkness,  necessarily  producing  universal  death 
and  destruction.  I  have  lived  seven  of  those  hours, 
a  great  age,  being  no  less  than  four  hundred  and 
twenty  minutes  of  time.  How  very  few  of  us  con- 
tinue so  long!  I  have  seen  generations  born,  flour- 
ish, and  expire.  My  present  friends  are  the  children 
and  grandchildren  of  the  friends  of  my  youth,  who 
are  now,  alas,  no  more!    And  I  must  soon  follow 


1778] 


Essays 


65 


them;  for,  by  the  course  of  nature,  though  still  in 
health,  I  cannot  expect  to  live  above  seven  or  eight 
minutes  longer.  What  now  avails  all  my  toil  and 
labor  in  amassing  honey-dew  on  this  leaf,  which  I 
cannot  live  to  enjoy!  What  the  political  struggles 
I  have  been  engaged  in  for  the  good  of  my  com- 
patriot inhabitants  of  this  bush,  or  my  philosophical 
studies  for  the  benefit  of  our  race  in  general!  for  in 
politics  what  can  laws  do  without  morals?  Our 
present  race  of  ephemeras  will  in  a  course  of  minutes 
become  corrupt,  like  those  of  other  and  older  bushes, 
and  consequently  as  wretched.  And  in  philosophy 
how  small  our  progress!  Alas!  art  is  long,  and  life 
is  short!  My  friends  would  comfort  me  with  the 
idea  of  a  name  they  say  I  shall  leave  behind  me; 
and  they  tell  me  I  have  lived  long  enough  to  nature 
and  to  glory.  But  what  will  fame  be  to  an  ephemera 
who  no  longer  exists  ?  And  what  will  become  of  all 
history  in  the  eighteenth  hour,  when  the  world  it- 
self, even  the  whole  Moulin  Joly,  shall  come  to  its 
end  and  be  buried  in  universal  ruin?" 

To  me,  after  all  my  eager  pursuits,  no  solid  pleas- 
ures now  remain,  but  the  reflection  of  a  long  life 
spent  in  meaning  well,  the  sensible  conversation  of 
a  few  good  lady  ephemeras,  and  now  and  then  a  kind 
smile  and  a  tune  from  the  ever  amiable  Brillante.1 

B.  Franklin. 

1  The  substance  of  these  reflections  of  the  venerable  Ephemera 
appeared  in  The  Pennsylvania  Gazette,  of  which  Franklin  was  then 
editor  and  publisher,  December  4,  1735,  in  an  essay  "On  Human 
Vanity."  In  its  original  form  the  article  purports  to  be  a  communica- 
tion from  some  other  person.  In  the  above  letter  to  "the  ever  ami- 
able Brillante,"  it  was  doubtless  re- written  from  memory,  and  was 
much  improved  both  as  to  diction  and  sentiment. 


XIV 


THE  WHISTLE 

TO  MADAME  BRILLON 

1779- 

I  received  my  dear  friend's  two  letters,  one  for 
Wednesday  and  one  for  Saturday.  This  is  again 
Wednesday.  I  do  not  deserve  one  for  to-day,  be- 
cause I  have  not  answered  the  former.  But,  indolent 
as  I  am,  and  averse  to  writing,  the  fear  of  having  no 
more  of  your  pleasing  epistles,  if  I  do  not  contribute 
to  the  correspondence,  obliges  me  to  take  up  my  pen ; 
and  as  Mr.  B.  has  kindly  sent  me  word  that  he  sets 
out  to-morrow  to  see  you,  instead  of  spending  this 
Wednesday  evening,  as  I  have  done  its  namesakes,  in 
your  delightful  company,  I  sit  down  to  spend  it  in 
thinking  of  you,  in  writing  to  you,  and  in  reading 
over  and  over  again  your  letters. 

I  am  charmed  with  your  description  of  Paradise, 
and  with  your  plan  of  living  there;  and  I  approve 
much  of  your  conclusion,  that,  in  the  meantime,  we 
should  draw  all  the  good  we  can  from  this  world. 
In  my  opinion  we  might  all  draw  more  good  from  it 
than  we  do,  and  suffer  less  evil,  if  we  would  take  care 
not  to  give  too  much  for  whistles.  For  to  me  it 
seems  that  most  of  the  unhappy  people  we  meet  with 
are  become  so  by  neglect  of  that  caution. 

66 


Essays 


67 


You  ask-  what  I  mean?  You  love  stories,  and  will 
excuse  my  telling  one  of  myself. 

When  I  was  a  child  of  seven  years  old,  my  friends, 
on  a  holiday,  filled  my  pocket  with  coppers.  I  went 
directly  to  a  shop  where  they  sold  toys  for  children; 
and  being  charmed  with  the  sound  of  a  whistle,  that 
I  met  by  the  way  in  the  hands  of  another  boy,  I 
voluntarily  offered  and  gave  all  my  money  for  one. 
I  then  came  home,  and  went  whistling  all  over  the 
house,  much  pleased  with  my  whistle,  but  disturbing 
all  the  family.  My  brothers,  and  sisters,  and  cousins, 
understanding  the  bargain  I  had  made,  told  me  I  had 
given  four  times  as  much  for  it  as  it  was  worth ;  put 
me  in  mind  what  good  things  I  might  have  bought 
with  the  rest  of  the  money;  and  laughed  at  me  so 
much  for  my  folly,  that  I  cried  with  vexation;  and 
the  reflection  gave  me  more  chagrin  than  the  whistle 
gave  me  pleasure. 

This,  however,  was  afterwards  of  use  to  me,  the  im- 
pression continuing  on  my  mind ;  so  that  often,  when 
I  was  tempted  to  buy  some  unnecessary  thing,  I  said 
to  myself,  Don't  give  too  much  for  the  whistle;  and  I 
saved  my  money. 

As  I  grew  up,  came  into  the  world,  and  observed 
the  actions  of  men,  I  thought  I  met  with  many,  very 
many,  who  gave  too  much  for  the  whistle. 

When  I  saw  one  too  ambitious  of  court  favor, 
sacrificing  his  time  in  attendance  on  levees,  his  re- 
pose, his  liberty,  his  virtue,  and  perhaps  his  friends, 
to  attain  it,  I  have  said  to  myself,  This  man  gives 
too  much  for  his  whistle. 

When  I  saw  another  fond  of  popularity,  constantly 


68 


Benjamin  Franklin 


[1779 


employing  himself  in  political  bustles,  neglecting  his 
own  affairs,  and  ruining  them  by  that  neglect,  He 
pays,  indeed,  said  I,  too  much  for  his  whistle. 

If  I  knew  a  miser,  who  gave  up  every  kind  of  com- 
fortable living,  all  the  pleasure  of  doing  good  to  others, 
all  the  esteem  of  his  fellow-citizens,  and  the  joys  of 
benevolent  friendship,  for  the  sake  of  accumulating 
wealth,  Poor  man,  said  I,  you  pay  too  much  for  your 
whistle. 

When  I  met  with  a  man  of  pleasure,  sacrificing 
every  laudable  improvement  of  the  mind,  or  of  his 
fortune,  to  mere  corporeal  sensations,  and  ruining  his 
health  in  their  pursuit,  Mistaken  man,  said  I,  you  are 
providing  pain  for  yourself,  instead  of  pleasure;  you 
give  too  much  for  your  whistle. 

If  I  see  one  fond  of  appearance,  or  fine  clothes,  fine 
houses,  fine  furniture,  fine  equipages,  all  above  his 
fortune,  for  which  he  contracts  debts,  and  ends  his 
career  in  a  prison,  Alas!  say  I,  he  has  paid  dear,  very 
dear,  for  his  whistle. 

When  I  see  a  beautiful,  sweet-tempered  girl  mar- 
ried to  an  ill-natured  brute  of  a  husband,  What  a  pity, 
say  I,  that  she  should  pay  so  much  for  a  whistle! 

In  short,  I  conceive  that  great  part  of  the  miseries 
of  mankind  are  brought  upon  them  by  the  false  esti- 
mates they  have  made  of  the  value  of  things,  and  by 
their  giving  too  much  for  their  whistles. 

Yet  I  ought  to  have  charity  for  these  unhappy 
people,  when  I  consider  that,  with  all  this  wisdom  of 
which  I  am  boasting,  there  are  certain  things  in  the 
world  so  tempting,  for  example,  the  apples  of  King 
John,  which  happily  are  not  to  be  bought ;  for  if  they 


1779] 


Essays 


69 


were  put  to  sale  by  auction,  I  might  very  easily  be 
led  to  ruin  myself  in  the  purchase,  and  find  that  I 
had  once  more  given  too  much  for  the  whistle. 

Adieu,  my  dear  friend,  and  believe  me'  ever  yours 
very  sincerely  and  with  unalterable  affection, 

B.  Franklin. 


XV 


AURORA  BOREALIS  1 

1.  Air  heated  by  any  means  becomes  rarefied  and 
specifically  lighter  than  other  air  in  the  same  situation 
not  heated. 

2.  Air  being  thus  made  lighter  rises,  and  the  neigh- 
boring cooler,  heavier  air  takes  its  place. 

3.  If  in  the  middle  of  a  room  you  heat  the  air  by 
a  stove,  or  pot  of  burning  coals  near  the  floor,  the 
heated  air  will  rise  to  the  ceiling,  spread  there  over 
the  cooler  air  till  it  comes  to  the  cold  walls;  there 
being  condensed  and  made  heavier,  it  descends  to 
supply  the  place  of  that  cool  air  which  had  moved 
towards  the  stove  or  fire,  in  order  to  supply  the  place 
of  the  heated  air  which  had  ascended  from  the  space 
around  the  stove  or  fire. 

4.  Thus  there  will  be  a  continual  circulation  of  air 
in  the  room,  which  may  be  rendered  visible  by  mak- 
ing a  little  smoke;  for  that  smoke  will  rise  and  cir- 
culate with  the  air. 

1  First  published  in  Mr.  Vaughan's  edition  of  the  author's  writings. 
Mr.  Vaughan  says:  "If  I  mistake  not,  the  paper  was  read  at  the  Royal 
Academy  of  Sciences  at  Paris,  at  the  meeting  held  immediately  after 
Easter,  1779." 

70 


1779] 


Essays 


7i 


5.  A  similar  operation  is  performed  by  nature  on 
the  air  of  the  globe.  Our  atmosphere  is  of  a  certain 
height,  perhaps  at  a  medium  — ; —  miles.  Above  that 
height  it  is  so  rare  as  to  be  almost  a  vacuum.  The 
air  heated  between  the  tropics  is  continually  rising, 
and  its  place  is  supplied  by  northerly  and  southerly 
winds  which  come  from  those  cool  regions. 

6.  The  light,  heated  air,  floating  above  the  cooler 
and  denser,  must  spread  northward  and  southward, 
and  descend  near  the  two  poles,  to  supply  the  place 
of  the  cooler  air  which  had  moved  towards  the 
equator. 

7.  Thus  a  circulation  of  air  is  kept  up  in  our  at- 
mosphere as  in  the  room  above  mentioned. 

8.  That  heavier  and  lighter  air  may  move  in  cur- 
rents of  different  and  even  opposite  directions,  ap- 
pears sometimes  by  the  clouds  that  happen  to  be  in 
these  currents,  as  plainly  as  by  the  smoke  in  the  ex- 
periment above  mentioned.  Also  in  opening  a  door 
between  two  chambers,  one  of  which  has  been 
warmed,  by  holding  a  candle  near  the  top,  near  the 
bottom,  and  near  the  middle,  you  will  find  a  strong 
current  of  warm  air  passing  out  of  the  warmed  room 
above,  and  another  of  cool  air  entering  it  below,  while 
in  the  middle  there  is  little  or  no  motion. 

9.  The  great  quantity  of  vapor  rising  between  the 
tropics  forms  clouds,  which  contain  much  electricity. 

Some  of  them  fall  in  rain,  before  they  come  to  the 
polar  regions. 

10.  If  the  rain  be  received  in  an  isolated  vessel, 
the  vessel  will  be  electrified;  for  every  drop  brings 
down  some  electricity  with  it. 


72 


Benjamin  Franklin 


[1779 


1 1 .  The  same  is  done  by  snow  and  hail. 

12.  The  electricity  so  descending  in  temperate 
climates  is  received  and  imbibed  by  the  earth. 

13.  If  the  clouds  are  not  sufficiently  discharged  by 
this  means,  they  sometimes  discharge  themselves 
suddenly  by  striking  into  the  earth,  where  the  earth 
is  fit  to  receive  their  electricity. 

14.  The  earth  in  temperate  and  warm  climates  is 
generally  fit  to  receive  it,  being  a  good  conductor. 

15.  A  certain  quantity  of  heat  will  make  some  bodies 
good  conductors  that  will  not  otherwise  conduct. 

16.  Thus  wax  rendered  fluid,  and  glass  softened 
by  heat,  will  both  of  them  conduct. 

17.  And  water,  though  naturally  a  good  conductor, 
will  not  conduct  well  when  frozen  into  ice  by  a  com- 
mon degree  of  cold;  not  at  all  where  the  cold  is 
extreme. 

18.  Snow  falling  upon  frozen  ground  has  been 
found  to  retain  its  electricity;  and  to  communicate 
it  to  an  isolated  body,  when  after  falling  it  has  been 
driven  about  by  the  wind. 

19.  The  humidity,  contained  in  all  the  equatorial 
clouds  that  reach  the  polar  regions  must  there  be 
condensed  and  fall  in  snow. 

20.  The  great  cake  of  ice  that  eternally  covers 
those  regions  may  be  too  hard  frozen  to  permit  the 
electricity,  descending  with  that  snow,  to  enter  the 
earth. 

21.  It  will  therefore  be  accumulated  upon  that  ice. 

22.  The  atmosphere,  being  heavier  in  the  polar  re- 
gions than  in  the  equatorial,  will  there  be  lower;  as 
well  from  that  cause  as  from  the  smaller  effect  of  the 


1779]  Essays 


73 


centrifugal  force;  consequently  the  distance  to  the 
vacuum  above  the  atmosphere  will  be  less  at  the  poles 
than  elsewhere;  and  probably  much  less  than  the 
distance  (upon  the  surface  of  the  globe)  extending 
from  the  pole  to  those  latitudes  in  which  the  earth 
is  so  thawed  as  to  receive  and  imbibe  electricity;  the 
frost  continuing  to  latitude  80,  which  is  10  degrees 
or  600  miles  from  the  pole,  while  the  height  of  the 
atmosphere  there,  of  such  density  as  to  obstruct  the 
motion  of  the  electric  fluid,  can  scarce  be  estimated 
above  miles. 

23.  The  vacuum  above  is  a  good  conductor. 

24.  May  not,  then,  the  great  quantity  of  electricity 
brought  into  the  polar  regions  by  the  clouds,  which 
are  condensed  there,  and  fall  in  snow,  which  elec- 
tricity would  enter  the  earth,  but  cannot  penetrate 
the  ice;  may  it  not,  I  say  (as  a  bottle  overcharged) 
break  through  that  low  atmosphere  and  run  along 
in  the  vacuum  over  the  air  towards  the  equator,  di- 
verging as  the  degrees  of  longitude  enlarge,  strongly 
visible  where  densest,  and  becoming  less  visible  as  it 
more  diverges;  till  it  finds  a  passage  to  the  earth  in 
more  temperate  climates,  or  is  mingled  with  their 
upper  air? 

25.  If  such  an  operation  of  nature  were  really  per- 
formed, would  it  not  give  all  the  appearances  of  an 

AURORA  BOREALIS? 

26.  And  would  not  the  aurorae  become  more  fre- 
quent after  the  approach  of  winter;  not  only  because 
more  visible  in  the  longer  nights,  but  also  because  in 
summer  the  long  presence  of  the  sun  may  soften  the 
surface  of  the  great  ice  cake,  and  render  it  a  con- 


74 


Benjamin  Franklin 


[1779 


ductor,  by  which  the  accumulation  of  electricity  in 
the  polar  regions  will  be  prevented? 

27.  The  atmosphere  of  the  polar  regions  being  made 
more  dense  by  the  extreme  cold,  and  all  the  moisture 
in  that  air  being  frozen,  may  not  any  great  light  aris- 
ing therein,  and  passing  through  it,  render  its  density 
in  some  degree  visible  during  the  night-time,  to  those 
who  live  in  the  rarer  air  of  more  southern  latitudes? 
And  would  it  not,  in  that  case,  although  in  itself  a 
complete  and  full  circle,  extending  perhaps  ten  de- 
grees from  the  pole,  appear  to  spectators  so  placed 
(who  could  see  only  a  part  of  it)  in  the  form  of  a  seg- 
ment, its  chord  resting  on  the  horizon,  and  its  arch 
elevated  more  or  less  above  it,  as  seen  from  latitudes 
more  or  less  distant,  darkish  in  color,  but  yet  suffi- 
ciently transparent  to  permit  some  stars  to  be  seen 
through  it? 

28.  The  rays  of  electric  matter  issuing  out  of  a 
body  diverge  by  mutually  repelling  each  other,  un- 
less there  be  some  conducting  body  near  to  receive 
them;  and  if  that  conducting  body  be  at  a  greater 
distance,  they  will  -first  diverge,  and  then  converge,  in 
order  to  enter  it.  May  not  this  account  for  some  of 
the  varieties  of  figure  seen  at  times  in  the  motions  of 
the  luminous  matter  of  the  aurorae ;  since  it  is  possi- 
ble that,  in  passing  over  the  atmosphere  from  the 
north,  in  all  directions  or  meridians,  towards  the 
equator,  the  rays  of  that  matter  may  find  in  many 
places  portions  of  cloudy  region,  or  moist  atmosphere 
under  them,  which  (being  in  the  natural  or  negative 
state)  may  be  fit  to  receive  them,  and  towards  which 
they  may  therefore  converge ;  and  when  one  of  those 


1779] 


Essays 


75 


receiving  bodies  is  more  than  saturated,  they  may 
again  diverge  from  it,  towards  other  surrounding 
masses  of  such  humid  atmosphere,  and  thus  form  the 
crowns,  as  they  are  called,  and  other  figures  men- 
tioned in  the  histories  of  this  meteor? 

29.  If  it  be  true  that  the  clouds  which  go  to  the 
polar  regions  carry  thither  the  vapors  of  the  equa- 
torial and  temperate  regions,  which  vapors  are  con- 
densed by  the  extreme  cold  of  the  polar  regions  and 
fall  in  snow  or  hail,  the  winds  which  come  from 
those  regions  ought  to  be  generally  dry,  unless  they 
gain  some  humidity  by  sweeping  the  ocean  in  their 
way;  and,  if  I  mistake  not,  the  winds  between  the 
northwest  and  northeast  are  for  the  most  part  dry, 
when  they  have  continued  some  time.1 

[In  the  Philosophical  Transactions  for  1774,  p.  128, 
is  a  letter  from  Mr.  J.  S.  Winn,  to  Dr.  Franklin,  stating 
that  since  he  had  first  made  the  observation  concerning 
the  south  or  southwest  winds  succeeding  an  aurora,  he 
had  found  it  invariably  obtaining  in  twenty-three  in- 
stances ;  and  he  adds  in  a  note  a  fresh  confirming  instance. 
In  reply,  Dr.  Franklin  makes  the  following  conjecture.] 

The  aurora  borealis,  though  visible  almost  every 
night  of  clear  weather  in  the  more  northern  regions, 
and  very  high  in  the  atmosphere,  can  scarce  be  visible 
in  England  but  when  the  atmosphere  is  pretty  clear 
of  clouds  for  the  whole  space  between  us  and  those 
regions*   and  therefore  are  seldom  visible  there. 

1  In  one  of  the  copies  of  this  paper  there  is  a  line  drawn  across  this 
last  article.— W.  T.  F. 

This  paragraph  is  not  contained  in  Mr.  Vaughan's  edition,  and  was 
probably  not  communicated  to  him  by  the  author. 


76 


Benjamin  Franklin 


This  extensive  clearness  may  have  been  produced  by 
a  long  continuance  of  northerly  winds.  When  the 
winds  have  long  continued  in  one  quarter,  the  return 
is  often  violent.  Allowing  the  fact  so  [repeatedly  ob- 
served by  Mr.  Winn,  perhaps  this  may  account  for 
the  violence  of  the  southerly  winds,  that  soon  follow 
the  appearance  of  the  aurora  on  our  coasts. 


XVI 


AN  ECONOMICAL  PROJECT 

To  the  Authors  of  the  Journal  of  Paris: 

Messieurs  : — You  often  entertain  us  with  accounts 
of  new  discoveries.  Permit  me  to  communicate  to 
the  public,  through  your  paper,  one  that  has  lately 
been  made  by  myself,  and  which  I  conceive  may  be 
of  great  utility. 

I  was  the  other  evening  in  a  grand  company,  where 
the  new  lamp  of  Messrs.  Quinquet  and  Lange  was 
introduced,  and  much  admired  for  its  splendor;  but 
a  general  inquiry  was  made,  whether  the  oil  it  con- 
sumed was  not  in  proportion  to  the  light  it  afforded, 
in  which  case  there  would  be  no  saving  in  the  use  of 
it.  No  one  present  could  satisfy  us  in  that  point, 
which  all  agreed  ought  to  be  known,  it  being  a  very 
desirable  thing  to  lessen,  if  possible,  the  expense  of 
lighting  our  apartments,  when  every  other  article  of 
family  expense  was  so  much  augmented. 

I  was  pleased  to  see  this  general  concern  for  econ- 
omy, for  I  love  economy  exceedingly. 

I  went  home,  and  to  bed,  three  or  four  hours  after 
midnight,  with  my  head  full  of  the  subject.  An  acci- 
dental sudden  noise  waked  me  about  six  in  the  morn- 

77 


78 


Benjamin  Franklin 


[1779 


ing,  when  I  was  surprised  to  find  my  room  filled  with 
light;  and  I  imagined  at  first  that  a  number  ofjthose 
lamps  had  been  brought  into  it;  but,  rubbing  my 
eyes,  I  perceived  the  light  came  in  at  the  windows. 
I  got  up  and  looked  out  to  see  what  might  be  the 
occasion  of  it,  when  I  saw  the  sun  just  rising  above 
the  horizon,  whence  he  poured  his  rays  plentifully 
into  my  chamber,  my  domestic  having  negligently 
omitted,  the  preceding  evening,  to  close  the  shutters. 
I  looked  at  my  watch,  which  goes  very  well,  and 
found  that  it  was  but  six  o'clock;  and  still  thinking 
it  something  extraordinary  that  the  sun  should  rise 
so  early,  I  looked  into  the  almanac,  where  I  found  it 
tc  be  the  hour  given  for  his  rising  on  that  day.  I 
looked  forward,  too,  and  found  he  was  to  rise  still 
earlier  every  day  till  towards  the  end  of  June;  and 
that  at  no  time  in  the  year  he  retarded  his  rising  so 
long  as  till  eight  o  'clock.  Your  readers,  who  with  me 
have  never  seen  any  signs  of  sunshine  before  noon, 
and  seldom  regard  the  astronomical  part  of  the  alma- 
nac, will  be  as  much  astonished  as  I  was,  when  they 
hear  of  his  rising  so  early;  and  especially  when  I 
assure  them  that  he  gives  light  as  soon  as  he  rises.  I 
am  convinced  of  this.  I  am  certain  of  my  fact.  One 
cannot  be  more  certain  of  any  fact.  I  saw  it  with 
my  own  eyes.  And,  having  repeated  this  observa- 
tion the  three  following  mornings,  I  found  always 
precisely  the  same  result. 

Yet  it  so  happens  that,  when  I  speak  of  this  dis- 
covery to  others,  I  can  easily  perceive  by  their  coun- 
tenances, though  they  forbear  expressing  it  in  words, 
that  they  do  not  quite  believe  me.    One,  indeed,  who 


1779] 


Essays 


79 


is  a  learned  natural  philosopher,  has  assured  me  that 
I  must  certainly  be  mistaken  as  to  the  circumstance 
of  the  light  coming  into  my  room;  for  it  being  well 
known,  as  he  says,  that  there  could  be  no  light  abroad 
at  that  hour,  it  follows  that  none  could  enter  from 
without;  and  that  of  consequence,  my  windows  being 
accidentally  left  open,  instead  of  letting  in  the  light, 
had  only  served  to  let  out  the  darkness ;  and  he  used 
many  ingenious  arguments  to  show  me  how  I  might, 
by  that  means,  have  been  deceived.  I  owned  that  he 
puzzled  me  a  little,  but  he  did  not  satisfy  me;  and 
the  subsequent  observations  I  made,  as  above  men- 
tioned, confirmed  me  in  my  first  opinion. 

This  event  has  given  rise  in  my  mind  to  several 
serious  and  important  reflections.  I  considered  that 
if  I  had  not  been  awakened  so  early  in  the  morning  I 
should  have  slept  six  hours  longer  by  the  light  of  the 
sun,  and  in  exchange  have  lived  six  hours  the  follow- 
ing night  by  candle-light,  and  the  latter  being  a  much 
more  expensive  light  than  the  former,  my  love  of 
economy  induced  me  to  muster  up  what  little  arith- 
metic I  was  master  of,  and  to  make  some  calculations 
which  I  shall  give  you,  after  observing  that  utility  is, 
in  my  opinion,  the  test  of  value  in  matters  of  inven- 
tion, and  that  a  discovery  which  can  be  applied  to  no 
use,  or  is  not  good  for  something,  is  good  for  nothing. 

I  took  for  the  basis  of  my  calculation  the  supposi- 
tion that  there  are  one  hundred  thousand  families  in 
Paris,  and  that  these  families  consume  in  the  night 
half  a  pound  of  bougies,  or  candles,  per  hour.  I 
think  this  is  a  moderate  allowance,  taking  one  family 
with  another;  for  though  I  believe  some  consume 


8o 


Benjamin  Franklin 


[1779 


less,  I  know  that  many  consume  a  great  deal  more. 
Then  estimating  seven  hours  per  day  as  the  medium 
quantity  between  the  time  of  the  sun's  rising  and 
ours,  he  rising  during  the  six  following  months  from 
six  to  eight  hours  before  noon,  and  there  being  seven 
hours,  of  course,  per  night,  in  which  we  burn  candles, 
the  account  will  stand  thus : 

In  the  six  months  between  the  20th  of  March  and 
the  20th  of  September  there  are 

Nights  183 

Hours  of  each  night  in  which  We  burn 

candles   7 

Multiplication  gives  for  the  total  num- 
ber of  hours  1,281 

These  1,281  hours  multiplied  by  100,000, 

the  number  of  inhabitants,  give     .  128,100,000 

One  hundred  twenty-eight  millions  and 
one  hundred  thousand  hours  spent 
at  Paris  by  candle-light,  which,  at 
half  a  pound  of  wax  and  tallow  per 
hour,  gives  the  weight  of      .       .  64,050,000 

Sixty-four  millions  and  fifty  thousands 
of  pounds,  which,  estimating  the 
whole  at  the  medium  price  of  thirty 
sols  the  pound,  makes  the  sum  of 
ninety-six  millions  and  seventy- 
five  thousand  livres  tournois  .       .  96,075,000 

An  immense  sum,  that  the  city  of  Paris  might  save 
every  year  by  the  economy  of  using  sunshine  instead 
of  candles! 


1779] 


Essays 


81 


If  it  should  be  said  that  people  are  apt  to  be  ob- 
stinately attached  to  old  customs,  and  that  it  will  be 
difficult  to  induce  them  to  rise  before  noon,  conse- 
quently my  discovery  can  be  of  little  use,  I  answer, 
Nil  desperandum.  I  believe  all  who  have  common- 
sense,  as  soon  as  they  have  learnt  from  this  paper 
that  it  is  daylight  when  the  sun  rises,  will  contrive  to 
rise  with  him,  and,  to  compel  the  rest,  I  would  pro- 
pose the  following  regulations: 

First.  Let  a  tax  be  laid  of  a  louis  per  window  on 
every  window  that  is  provided  with  shutters  to  keep 
out  the  light  of  the  sun. 

Second.  Let  the  same  salutary  operation  of  po- 
lice be  made  use  of,  to  prevent  our  burning  candles, 
that  inclined  us  last  winter  to  be  more  economical  in 
burning  wood;  that  is,  let  guards  be  placed  in  the 
shops  of  the  wax  and  tallow  chandlers,  and  no  family 
be  permitted  to  be  supplied  with  more  than  one 
pound  of  candles  per  week. 

Third.  Let  guards  also  be  posted  to  stop  all  the 
coaches,  etc.,  that  would  pass  the  streets  after  sun- 
set, except  those  of  physicians,  surgeons,  and  mid- 
wives. 

Fourth.  Every  morning,  as  soon  as  the  sun  rises, 
let  all  the  bells  in  every  church  be  set  ringing;  and 
if  that  is  not  sufficient,  let  cannon  be  fired  in  every 
street,  to  wake  the  sluggards  effectually,  and  make 
them  open  their  eyes  to  see  their  true  interest. 

All  the  difficulty  will  be  in  the  first  two  or  three 
days  after  which  the  reformation  will  be  as  natural 
and  easy  as  the  present  irregularity;  for,  ce  n'est  que 
le  premier  pas  qui  coute.    Oblige  a  man  to  rise  at 


82 


Benjamin  Franklin 


[1779 


four  in  the  morning,  and  it  is  more  than  probable  he 
will  go  willingly  to  bed  at  eight  in  the  evening;  and, 
having  had  eight  hours'  sleep,  he  will  rise  more  will- 
ingly at  four  in  the  morning  following.  But  this 
sum  of  ninety-six  millions  and  seventy-five  thousand 
livres  is  not  the  whole  of  what  may  be  saved  by  my 
economical  project.  You  may  observe  that  I  have 
calculated  upon  only  one  half  of  the  year,  and  much 
may  be  saved  in  the  other,  though  the  days  are 
shorter.  Besides,  the  immense  stock  of  wax  and 
tallow  left  unconsumed  during  the  summer  will 
probably  make  candles  much  cheaper  for  the  ensuing 
winter,  and  continue  them  cheaper  as  long  as  the 
proposed  reformation  shall  be  supported. 

For  the  great  benefit  of  this  discovery,  thus  freely 
communicated  and  bestowed  by  me  on  the  public,  I 
demand  neither  place,  pension,  exclusive  privilege, 
nor  any  other  reward  whatever.  I  expect  only  to 
have  the  honor  of  it.  And  yet  I  know  there  are  lit- 
tle, envious  minds  who  will,  as  usual,  deny  me  this, 
and  say  that  my  invention  was  known  to  the  an- 
cients, and  perhaps  they  may  bring  passages  out  of 
the  old  books  in  proof  of  it.  I  will  not  dispute  with 
these  people  that  the  ancients  knew  not  that  the  sun 
would  rise  at  certain  hours ;  they  possibly  had,  as  we 
have,  almanacs  that  predicted  it,  but  it  does  not 
follow  thence  that  they  knew  he  gave  light  as  soon  as 
he  rose.  This  is  what  I  claim  as  my  discovery.  If  the 
ancients  knew  it,  it  must  have  been  long  since  for- 
gotten ;  for  it  certainly  was  unknown  to  the  moderns 
at  least  to  the  Parisians,  which  to  prove  I  need  use 
but  one  plain  simple  argument.    They  are  as  well  in- 


1779] 


Essays 


83 


structed,  judicious,  and  prudent  a  people  as  exist 
anywhere  in  the  world,  all  professing,  like  myself,  to 
be  lovers  of  economy,  and  from  the  many  heavy 
taxes  required  from  them  by  the  necessities  of  the 
state,  have  surely  an  abundant  reason  to  be  economi- 
cal. I  say  it  is  impossible  that  so  sensible  a  people, 
under  such  circumstances,  should  have  lived  so  long 
by  the  smoky,  unwholesome,  and  enormously  expen- 
sive light  of  candles,  if  they  had  really  known  that 
they  might  have  had  as  much  pure  light  of  the  sun 
for  nothing.    I  am,  etc., 

A  Subscriber. 


XVII 


TO  EDWARD  NAIRNE,  OF  LONDON 

READ  AT  A  MEETING  OF  THE  AMERICAN  PHILOSOPHICAL  SOCIETY, 
JANUARY  26,  1786. 

Passy,  near  Paris,  13  November,  1780. 

Sir  : — The  qualities  hitherto  sought  in  a  hygrome- 
ter, or  instrument  to  discover  the  degrees  of  moisture 
and  dryness  in  the  air,  seem  to  have  been,  an  aptitude 
to  receive  humidity  readily  from  a  moist  air,  and  to 
part  with  it  as  readily  to  a  dry  air.  Different  sub- 
stances have  been  found  to  possess  more  or  less  of 
this  quality ;  but  when  we  shall  have  found  the  sub- 
stance that  has  it  in  the  greatest  perfection,  there  will 
still  remain  some  uncertainty  in  the  conclusions  to  be 
drawn  from  the  degree  shown  by  the  instrument, 
arising  from  the  actual  state  of  the  instrument  itself 
as  to  heat  and  cold.  Thus,  if  two  bottles  or  vessels 
of  glass  or  metal  being  filled,  the  one  with  cold  and 
the  other  with  hot  water,  are  brought  into  a  room, 
the  moisture  of  the  air  in  the  room  will  attach  itself 
in  quantities  to  the  surface  of  the  cold  vessel ;  while, 
if  you  actually  wet  the  surface  of  the  hot  vessel,  the 
moisture  will  immediately  quit  it,  and  be  absorbed  by 
the  same  air.  And  thus,  in  a  sudden  change  in  the 
84 


Essays 


85 


air  from  cold  to  warm,  the  instrument  remaining 
longer  cold  may  condense  and  absorb  more  moisture, 
and  mark  the  air  as  having  become  more  humid  than 
it  is  in  reality,  and  the  contrary  in  a  change  from 
warm  to  cold. 

But,  if  such  a  sudden  changing  instrument  could 
be  freed  from  these  imperfections,  yet,  when  the  de- 
sign is  to  discover  the  different  degrees  of  humidity 
in  the  air  of  different  countries,  I  apprehend  the 
quick  sensibility  of  the  instrument  to  be  rather  a 
disadvantage ;  since,  to  draw  the  desired  conclusions 
from  it,  a  constant  and  frequent  observation  day  and 
night  in  each  country  will  be  necessary  for  a  year 
or  years,  and  the  mean  of  each  different  set  of  ob- 
servations is  to  be  found  and  determined.  After 
all  which,  some  uncertainty  will  remain  respecting 
the  different  degrees  of  exactitude  with  which  differ- 
ent persons  may  have  made  and  taken  notes  of  their 
observations. 

For  these  reasons  I  apprehend  that  a  substance 
which,  though  capable  of  being  distended  by  mois- 
ture and  contracted  by  dryness,  is  so  slow  in  receiv- 
ing and  parting  with  its  humidity,  that  the  frequent 
changes  in  the  atmosphere  have  not  time  to  affect  it 
sensibly,  and  which  therefore  should  gradually  take 
nearly  the  medium  of  all  those  changes  and  preserve 
it  constantly,  would  be  the  most  proper  substance 
of  which  to  make  such  an  hygrometer. 

Such  an  instrument,  you,  my  dear  sir,  though  with- 
out intending  it,  have  made  for  me;  and  I,  without 
desiring  or  expecting  it,  have  received  from  you.  It 
is  therefore  with  propriety  that  I  address  to  you  the 


86 


Benjamin  Franklin 


following  account  of  it;  and  the  more  as  you  have 
both  a  head  to  contrive  and  a  hand  to  execute  the 
means  of  perfecting  it.  And  I  do  this  with  greater 
pleasure,  as  it  affords  me  the  opportunity  of  renewing 
that  ancient  correspondence  and  acquaintance  with 
you,  which  to  me  was  always  so  pleasing  and  so 
instructive. 

You  may  possibly  remember  that,  in  or  about  the 
year  1758,  you  made  for  me  a  set  of  artificial  magnets, 
six  in  number,  each  five  inches  and  a  half  long,  half 
an  inch  broad,  and  one  eighth  of  an  inch  thick.  These, 
with  two  pieces  of  soft  iron,  which  together  equalled 
one  of  the  magnets,  were  enclosed  in  a  little  box  of 
mahogany  wood,  the  grain  of  which  ran  with,  and  not 
across,  the  length  of  the  box;  and  the  box  was  closed 
by  a  little  shutter  of  the  same  wood,  the  grain  of 
which  ran  across  the  box ;  and  the  ends  of  this  shut- 
ting piece  were  bevelled  so  as  to  fit  and  slide  in  a  kind 
of  dovetail  groove  when  the  box  was  to  be  shut  or 
opened. 

I  had  been  of  opinion  that  good  mahogany  wood 
was  not  affected  by  moisture  so  as  to  change  its  di- 
mensions, and  that  it  was  always  to  be  found  as  the 
tools  of  the  workmen  left  it.  Indeed  the  difference 
at  different  times  in  the  same  country  is  so  small  as 
to  be  scarcely  in  a  common  way  observable.  Hence 
the  box,  which  was  made  so  as  to  allow  sufficient 
room  for  the  magnets  to  slide  out  and  in  freely,  and, 
when  in,  afforded  them  so  much  play  that  by  shaking 
the  box  one  could  make  them  strike  the  opposite 
sides  alternately,  continued  in  the  same  state  all  the 
time  I  remained  in  England,  which  was  four  years, 


Essays 


87 


without  any  apparent  alteration.  I  left  England 
in  August,  1762,  and  arrived  at  Philadelphia  in  Octo- 
ber the  same  year.  In  a  few  weeks  after  my  arrival, 
being  desirous  of  showing  your  magnets  to  a  philo- 
sophical friend,  I  found  them  so  tight  in  the  box  that 
it  was  with  difficulty  I  got  them  out ;  and  constantly, 
during  the  two  years  I  remained  there,  viz.,  till 
November,  1764,  this  difficulty  of  getting  them  out 
and  in  continued.  The  little  shutter  too,  as  wood 
does  not  shrink  lengthways  of  the  grain,  was  found 
too  long  to  enter  its  grooves,  and,  not  being  used, 
was  mislaid  and  lost;  and  I  afterwards  had  another 
made  that  fitted. 

In  December,  1764,  I  returned  to  England,  and 
after  some  time  I  observed  that  my  box  was  become 
full  big  enough  for  my  magnets,  and  too  wide  for  my 
new  shutter,  which  was  so  much  too  short  for  its 
grooves  that  it  was  apt  to  fall  out,  and  to  make  it 
keep  in  I  lengthened  it  by  adding  to  each  end  a  little 
coat  of  sealing-wax. 

I  continued  in  England  more  than  ten  years,  and 
during  all  that  time,  after  the  first  change,  I  per- 
ceived no  alteration.  The  magnets  had  the  same 
freedom  in  their  box,  and  the  little  shutter  continued 
with  the  added  sealing-wax  to  fit  its  grooves,  till 
some  weeks  after  my  second  return  to  America. 

As  I  could  not  imagine  any  other  cause  for  this 
change  of  dimensions  in  the  box,  when  in  the  differ- 
ent countries,  I  concluded,  first  generally,  that  the  air 
of  England  was  moister  than  that  of  America.  And 
this  I  supposed  an  effect  of  its  being  an  island,  where 
every  wind  that  blew  must  necessarily  pass  over 


88  Benjamin  Franklin  [1780 

some  sea  before  it  arrived,  and  of  course  lick  up  some 
vapor.  I  afterwards  indeed  doubted  whether  it 
might  be  just  only  so  far  as  related  to  the  city  of  Lon- 
don, where  I  resided,  because  there  are  many  causes 
of  moisture  in  the  city  air  which  do  not  exist  to  the 
same  degree  in  the  country,  such  as  the  brewers'  and 
dyers'  boiling  caldrons,  and  the  great  number  of  pots 
and  tea-kettles  continually  on  the  fire,  sending  forth 
abundance  of  vapor,  and  also  the  number  of  animals 
who  by  their  breath  continually  increase  it ;  to  which 
may  be  added,  that  even  the  vast  quantity  of  sea 
coals  burnt  there  do,  in  kindling,  discharge  a  great 
deal  of  moisture. 

When  I  was  in  England  the  last  time,  you  also 
made  for  me  a  little  achromatic  pocket  telescope; 
the  body  was  brass,  and  it  had  a  round  case  (I  think 
of  thin  wood)  covered  with  shagreen.  All  the  while 
I  remained  in  England,  though  possibly  there  might 
be  some  small  changes  in  the  dimensions  of  this  case, 
I  neioher  perceived  nor  suspected  any.  There  was 
always  comfortable  room  for  the  telescope  to  slip 
in  and  out.  But  soon  after  I  arrived  in  America, 
which  was  in  May,  1775,  the  case  became  too  small 
for  the  instrument.  It  was  with  much  difficulty  and 
various  contrivances  that  I  got  it  out,  and  I  could 
never  after  get  it  in  again  during  my  stay  there, 
which  was  eighteen  months.  I  brought  it  with  me 
to  Europe,  but  left  the  case  as  useless,  imagining 
that  I  should  find  the  continental  air  of  France  as 
dry  as  that  of  Pennsylvania,  where  my  magnet-box 
had  also  returned  a  second  time  to  its  narrowness, 
and  pinched  the  pieces,  as  heretofore,  obliging  me, 


78o] 


Essays 


89 


too,  to  scrape  the  sealing-wax  off  the  ends  of  the 
shutter. 

I  had  not  been  long  in  France  before  I  was  stir- 
prised  to  find  that  my  box  was  become  as  large  as  it 
had  always  been  in  England;  the  magnets  entered 
and  came  out  with  the  same  freedom,  and,  when  in,  I 
could  rattle  them  against  its  sides ;  this  has  continued 
to  be  the  case  without  sensible  variation.  My  habi- 
tation is  out  of  Paris,  distant  almost  a  league,  so  that 
the  moist  air  of  the  city  cannot  be  supposed  to  have 
much  effect  upon  the  box.  I  am  upon  a  high,  dry 
hill,  in  a  free  air,  as  likely  to  be  dry  as  any  air  in 
France.  Whence  it  seems  probable  that  the  air  of 
England  in  general  may,  as  well  as  that  of  London, 
be  moister  than  the  air  of  America,  since  that  of 
France  is  so,  and  in  a  part  so  distant  from  the  sea. 

The  greater  dryness  of  the  air  in  America  appears 
from  some  other  observations .  The  cabinet  work  for- 
merly sent  us  from  London,  which  consisted  in  thin 
plates  of  fine  wood  glued  upon  fir,  never  would  stand 
with  us;  the  veneering,  as  those  plates  are  called, 
would  get  loose  and  come  off;  both  woods  shrinking, 
and  their  grains  often  crossing,  they  were  for  ever 
cracking  and  flying.  And  in  my  electrical  experi- 
ments there,  it  was  remarkable  that  a  mahogany 
table,  on  which  my  jars  stood  under  the  prime 
conductor  to  be  charged,  would  often  be  so  dry,  par- 
ticularly when  the  wind  had  been  some  time  at 
northwest,  which  with  us  is  a  very  drying  wind,  as  to 
isolate  the  jars,  and  prevent  their  being  charged  till 
I  had  formed  a  communication  between  their  coat- 
ings and  the  earth.    I  had  a  like  table  in  London, 


90  Benjamin  Franklin  [i780 

which  I  used  for  the  same  purpose  all  the  time  I 
resided  there;  but  it  was  never  so  dry  as  to  refuse 
conducting  the  electricity. 

Now  what  I  would  beg  leave  to  recommend  to  you, 
is,  that  you  would  recollect,  if  you  can,  the  species  of 
mahogany  of  which  you  made  my  box,  for  you  know 
there  is  a  good  deal  of  difference  in  woods  that  go 
under  that  name;  or,  if  that  cannot  be,  that  you 
would  take  a  number  of  pieces  of  the  closest  and  fin- 
est grained  mahogany  that  you  can  meet  with,  plane 
them  to  the  thinness  of  about  a  line,  and  the  width 
of  about  two  inches  across  the  grain,  and  fix  each 
of  the  pieces  in  some  instrument  that  you  can  con- 
trive, which  will  permit  them  to  contract  and  dilate, 
and  will  show,  in  sensible  degrees,  by  a  movable  hand 
upon  a  marked  scale,  the  otherwise  less  sensible 
quantities  of  such  contraction  and  dilatation.  If 
these  instruments  are  all  kept  in  the  same  place  while 
making,  and  are  graduated  together  while  subject 
to  the  same  degrees  of  moisture  or  dryness,  I  appre- 
hend you  will  have  so  many  comparable  hygrometers 
which,  being  sent  into  different  countries,  and  con- 
tinued there  for  some  time,  will  find  and  show  there 
the  mean  of  the  different  dryness  and  moisture  of 
the  air  of  those  countries  and  that  with  much  less 
trouble  than  by  any  hygrometer  hitherto  in  use. 
With  great  esteem,  I  am,  dear  sir,  your  most  obedient 
and  most  humble  servant, 

B.  Franklin. 


XVIII 


TO  JOHN  INGENHOUSZ 

1.  When  the  subtile  fluid,  which  we  call  fire  or 
heat,  enters  a  solid  body,  it  separates  the  particles 
of  which  that  body  consists  farther  from  each  other, 
and  thus  dilates  the  body,  increasing  its  dimensions. 

2.  A  greater  proportion  of  fire  introduced  sepa- 
rates the  parts  so  far  from  each  other  that  the  solid 
body  becomes  a  fluid,  being  melted. 

3.  A  still  greater  quantity  of  heat  separates  parts 
so  far  that  they  lose  their  mutual  attraction,  and 
acquire  a  mutual  repulsion,  whence  they  fly  from 
each  other,  either  gradually  or  suddenly,  with  great 
force,  as  the  separating  power  is  introduced  gradu- 
ally or  suddenly. 

4.  Thus  ice  becomes  water,  and  water  vapor, 
which  vapor  is  said  to  expand  fourteen  thousand 
times  the  space  it  occupied  in  the  form  of  water, 
and  with  an  explosive  force  in  certain  cases  capable 
of  producing  great  and  violent  effects. 

5.  Thus  metals  expand,  melt,  and  explode;  the 
two  first  effected  by  the  gradual  application  of  the 
separating  power,  and  all  three,  in  its  sudden  appli- 
cation, by  artificial  electricity  or  lightning. 

6.  That  fluid,  in  passing  through  a  metal  rod 
or  wire,  is  generally  supposed  to  occupy  the 
whole  dimension  of  the  rod.    If  the  rod  is  smaller 

91 


92 


Benjamin  Franklin 


[1782 


in  some  places  than  in  others,  the  quantity  of  fluid, 
which  is  not  sufficient  to  make  any  change  in  the 
larger  or  thicker  part,  may  be  sufficient  to  expand, 
melt,  or  explode  the  smaller,  the  quantity  of  fluid 
passing  being  the  same,  and  the  quantity  of  matter 
less  that  is  acted  upon. 

7.  Thus  the  links  of  a  brass  chain,  with  a  certain 
quantity  of  electricity  passing  through  them,  have 
been  melted  in  the  small  parts  that  form  their  con- 
tact, while  the  rest  have  not  been  affected. 

8.  Thus  a  piece  of  tinfoil  cut  in  this  form,  en- 
closed in  a  pack  of  cards,  and  having  the  charge  of  a 
large  bottle  sent  through  it,  has  been  found  un- 
changed in  the  broadest  part,  between  a  and  b, 
melted  only  in  spots  between  c  and  d,  and  the  part 
between  d  and  e  reduced  to  smoke  by  explosion. 

9.  The  tinfoil  melted  in  spots  between  b  and  c  and 
that  whole  space  not  being  melted,  seems  to  indicate 
that  the  foil  in  the  melted  parts  had  been  thinner 
than  the  rest,  on  which  thin  parts  the  passing  fluid 
had  therefore  a  greater  effect. 

10.  Some  metals  melt  more  easily  than  others; 
tin  more  easily  than  copper,  copper  than  iron.  It 
is  supposed  (perhaps  not  yet  proved)  that  those 
which  melt  with  the  least  of  the  separating  power, 
whether  that  be  common  fire  or  the  electric  fluid, 
do  also  explode  with  less  of  that  power. 

11.  The  explosions  of  metal,  like  those  of  gun- 
powder, act  in  all  directions.  Thus  the  explosion  of 
gold-leaf  between  plates  of  glass,  breaking  the  glass 
to  pieces,  will  throw  those  pieces  into  all  parts  of  the 
room;  and  the  explosion  of  iron,  or  even  of  water, 


1782] 


Essays 


93 


94  Benjamin  Franklin  [1782 

between  the  joints  of  stone  in  a  steeple,  will  scatter 
the  stones  in  all  directions  round  the  neighborhood. 
But  the  direction  given  to  those  stones  by  the  ex- 
plosion is  to  be  considered  as  different  from  the 
direction  of  the  lightning  which  happened  to  occa- 
sion those  explosions  of  the  matter  it  met  with  in 
its  passage  between  the  clouds  and  the  earth. 

12.  When  bodies  positively  electrized  approach 
sharp-pointed  rods  or  thin  plates  of  metal,  these  are 
more  easily  rendered  negative  by  the  repulsive  force 
of  the  electric  fluid  in  those  positively  electrized 
bodies,  which  chases  away  the  natural  quantity  con- 
tained in  those  mince  rods  or  plates,  though  it  would 
not  have  force  enough  to  chase  the  same  out  of 
larger  masses.  Hence  such  points,  rods,  and  plates, 
being  in  a  negative  state,  draw  to  themselves  more 
strongly  and  in  greater  quantities  the  electric  fluid 
offered  them,  than  such  masses  can  do  which  remain 
nearly  in  their  natural  state.  And  thus  a  pointed 
rod  receives  not  only  at  its  point,  though  more  vis- 
ibly there,  but  at  all  parts  of  its  length  that  are 
exposed.  Hence  a  needle  held  between  the  finger 
and  thumb,  and  presented  to  a  charged  prime  con- 
ductor, will  draw  off  the  charge  more  expeditiously 
if  held  near  the  eye,  and  the  rest  of  its  length  is 
exposed  to  the  electrical  atmosphere,  than  if  all  but 
half  an  inch  of  the  point  is  concealed  and  covered. 

13.  Lightning  so  differs  from  solid  projectiles,  and 
from  common  fluids  projected  with  violence  that, 
though  its  course  is  rapid,  it  is  most  easily  turned  to 
follow  the  direction  of  good  conductors.  And  it  is 
doubted  whether  any  experiments  in  electricity  have 


i782] 


Essays 


95 


yet  decisively  proved  that  the  electric  fluid  in  its 
violent  passage  through  the  air  where  a  battery  is 
discharged  has  what  we  call  a  momentum,  which 
would  make  it  continue  its  course  in  a  right  line, 
though  a  conductor  offered  near  that  course  to  give 
it  a  different  or  even  contrary  direction;  or  that  it 
has  a  force  capable  of  pushing  forward  or  overthrow- 
ing the  objects  it  strikes  against,  even  though  it 
sometimes  pierces  them.  Does  not  this  seem  to  in- 
dicate that  the  perforation  is  not  made  by  the  force 
of  a  projectile  passing  through,  but  rather  by  the 
explosion  or  the  dilatation,  in  passing,  of  a  subtile 
line  of  fluid  ? 

14.  Such  an  explosion  or  dilatation  of  a  line  of 
fluid,  passing  through  a  card,  would  raise  burrs 
around  the  hole,  sometimes  on  one  side,  sometimes 
on  the  other,  and  sometimes  on  both,  according 
to  the  disposition  of  the  part  of  the  paper  near  the 
surface,  without  any  regard  to  the  direction  of  the 
fluid. 

15.  Great  thanks  are  due  to  the  ingenious  philo- 
sopher who  examined  the  vane  at  Cremona,  and  who 
took  the  pains  to  describe  so  exactly  the  effects  of 
the  lightning  upon  it,  and  to  communicate  that  de- 
scription. The  fact  is  extremely  curious.  It  is  well 
worth  considering.  He  invites  to  that  considera- 
tion. He  has  fairly  given  his  own  opinion.  He  will 
with  candor  receive  that  of  others,  though  it  may 
happen  to  differ  from  his  own.  By  calmly  discuss- 
ing rather  than  by  warmly  disputing,  the  truth  is 
most  easily  obtained.  I  shall  give  my  opinion  freely, 
as  it  is  asked,  hoping  it  may  prove  the  true  one; 


96 


Benjamin  Franklin 


and  promising  myself,  if  otherwise,  the  honor  at 
least  of  acknowledging  frankly  my  error,  and  of  be- 
ing thankful  to  him  who  kindly  shows  it  to  me. 

1 6.  By  the  account  given  of  this  stroke  of  light- 
ning upon  the  steeple  of  Cremona,  it  appears  that  the 
rod  of  iron  or  spindle,  on  which  the  vane  turned,  was 
of  about  two  inches  circumference,  terminating  in  a 
cross  above  the  vane,  and  its  lower  end  fixed  in  a 
marble  pedestal. 

17.  That  the  plate  of  the  vane  was  copper,  eight 
or  nine  inches  wide,  and  near  twice  as  long.  That  it 
was  about  one  line  thick  near  the  spindle,  and  grow- 
ing thinner  insensibly  towards  the  other  end,  where 
its  thickness  did  not  exceed  three  quarters  of  a  line, 
the  weight  twenty  ounces  and  a  half. 

18.  That  the  copper  had  been  tinned  over. 

19.  That  the  marble  pedestal  was  split  by  the 
stroke  into  many  pieces,  and  scattered  over  the  roof, 
garden,  and  court  of  neighboring  buildings.  One 
piece  was  found  thrown  to  a  distance  of  forty  feet. 
The  spindle  was  broken  and  displaced,  and  the  vane 
thrown  on  the  roof  of  the  parsonage  house,  twenty 
feet  from  the  steeple. 

20.  That  the  vane  was  perforated  in  eighteen 
places,  the  holes  of  irregular  forms,  and  the  metal 
which  had  filled  them  pushed  outwards,  in  some  of 
them  on  one  side  of  the  vane,  in  others  on  the  other. 
The  copper  showed  marks  of  having  been  partly 
melted,  and  in  some  places  tin  and  copper  melted 
and  mixed  together.  There  were  marks  of  smoke 
in  several  places. 

21.  The  ragged  parts  bent  outwards  round  each 


1782] 


Essays 


97 


hole,  being  brought  back  to  their  original  flat  posi- 
tion, were  not,  though  evidently  a  little  thinned  and 
dilated,  sufficient  to  fill  the  place. 

22.  From  the  effects  described  (19),  it  is  clear  that 
the  quantity  of  lightning  which  fell  on  this  steeple 
at  Cremona  was  very  great. 

23.  The  vane  being  a  thin  plate  of  copper,  its 
edges  and  corners  may  be  considered  as  a  series  of 
points,  and,  being  therefore  sooner  rendered  negative 
by  the  repulsive  force  of  an  approaching  positive 
cloud  than  the  blunt  and  thick  iron  cross  (12),  was 
probably  first  struck,  and  thence  became  the  con- 
ductor of  that  great  quantity. 

24.  The  plate  of  which  the  vane  was  formed, 
being  thicker  near  the  spindle,  and  diminishing  in 
thickness  gradually  to  the  other  end  (17),  was  prob- 
ably not  of  copper  plated  by  passing  between  rollers, 
for  they  would  have  left  it  of  equal  thickness ;  but  of 
metal  plated  by  the  hammer.  The  surface,  too,  of 
rolled  copper  is  even  and  plain;  that  of  hammered 
is  generally  uneven,  with  hollows  occasioned  by  the 
impressions  of  the  hammer. 

25.  In  those  concave  impressions  the  metal  is 
thinner  than  it  is  around  them,  and  probably  thin- 
nest near  the  centre  of  each  impression. 

26.  The  lightning,  which  in  passing  through  the 
vane  was  not  sufficient  to  melt  its  thicker  parts, 
might  be  sufficient  to  melt  the  thinner  (6,  7,  8,  9), 
and  to  soften  those  that  were  in  the  middle  state. 

27.  The  part  of  the  tin  (18)  which  covered  the 
thinner  parts,  being  more  easily  melted  and  ex- 
ploded than  copper  (10),  might  possibly  be  exploded 


98  Benjamin  Franklin  [1782 

when  the  copper  was  but  melted.  The  smoke  ap- 
pearing in  several  places  (20)  is  a  proof  of  explosion. 

28.  There  might  probably  be  more  tin  in  the  con- 
cave impressions  of  the  hammer  on  one  side  of  the 
plate,  than  on  the  convex  part  of  those  impressions 
on  the  other.  Hence  stronger  explosions  on  the 
concave  side. 

29.  The  nature  of  these  explosions  is  to  act  vio- 
lently in  all  directions;  and  in  this  case,  being  near 
the  plate,  they  would  act  against  it  on  one  side, 
while  they  acted  against  the  air  on  the  other. 

30.  These  thin  parts  of  the  plate  being  at  the 
same  instant  partly  in  fusion,  and  partly  so  softened 
as  to  be  near  it,  the  softened  parts  were  pushed  out- 
wards, a  hole  made,  and  some  of  the  melted  parts 
blown  away ;  hence  there  was  not  left  metal  enough 
to  re-fill  the  vacancy  by  bending  back  the  ragged 
parts  to  their  places. 

31.  The  concave  impressions  of  the  hammer,  being 
indifferently  made  on  both  sides  of  the  plate,  it  is 
natural,  from  28,  29,  30,  that  the  pushing  outwards 
of  the  softened  metal  by  explosions,  should  be  on 
both  sides  of  the  plate  nearly  equal. 

32.  That  the  force  of  a  simple  electrical  explosion 
is  very  great,  appears  from  the  Geneva  experiment, 
wherein  a  spark  between  two  wires,  under  oil  in  a 
drinking-glass,  breaks  the  glass,  body,  stem,  and  foot, 
all  to  shivers. 

33.  The  electric  explosion  of  metal  acts  with  still 
more  force.  A  strip  of  leaf -gold  no  broader  than  a 
straw,  exploded  between  two  pieces  of  thick  looking- 
glass,  will  break  the  glass  to  pieces,  though  confined 


1782] 


Essays 


99 


by  the  screws  of  a  strong  press;  and,  between  two 
pieces  of  marble  pressed  together  by  a  weight  of 
twenty  pounds,  will  lift  that  weight.  Much  less 
force  is  necessary  to  move  the  melted  and  softened 
parts  of  a  thin  plate  of  copper. 

34.  This  explication  of  the  appearances  on  the 
vane  is  drawn  from  what  we  already  know  of  elec- 
tricity and  the  effects  of  lightning.  The  learned 
author  of  the  account  gives  a  different  but  very  in- 
genious one,  which  he  draws  from  the  appearances 
themselves.  The  matter  pushed  out  of  the  holes  is 
found,  that  of  some  on  one  side  of  the  plate,  and  of 
others  on  the  other.  Hence  he  supposes  them  to  be 
occasioned  (if  I  understand  him  right)  by  streams  or 
threads  of  electric  matter  of  different  and  contrary 
kinds,  rushing  violently  towards  each  other,  and 
meeting  with  the  vane,  so  accidentally  placed  as  to 
be  found  precisely  in  the  place  of  their  meeting,  where 
it  was  pierced  by  all  of  them,  they  all  striking  on 
both  its  sides  at  the  same  instant.  This,  however, 
is  so  extraordinary  an  accident  as  to  be,  in  the  au- 
thor's own  opinion,  almost  miraculous.  "Passer- 
anno"  (says  he)  "forse  piu  secoli  prima  che  ritorni 
tralle  infinite  combinazioni  un  caso  simile  a  quello 
della  banderuola  che  ora  abbiamo  per  mano.  Forza  e 
che  si  esaurisca  una  non  piu  udita  miniera  di  fulmini 
sopra  una  grande  citta,  pressoche  seminata  di  cam- 
panili  e  di  banderuole,  il  che  e  rarissimo ;  e  puo  ancora 
[cento  ?]  volte  cio  succedere,  senza  che  s'  incontri 
giammai  un  altera  banderuola  tanto  opportunamente 
situata  tra  i  limiti  della  fulminea  explosione." 

35.  But,  though  the  author's  explication  of  these 


100 


Benjamin  Franklin 


[1782 


appearances  of  the  vane  does  not  satisfy  me,  I  am 
not  so  confident  of  my  own  as  to  propose  its  being 
accepted  without  confirmation  by  experiment.  Those 
who  have  strong  electric  batteries  may  try  it  thus: 
form  a  little  vane  of  paper,  and  spot  it  on  both  sides 
by  attaching  small  pieces  of  leaf -gold,  or  tinfoil,  not 
exactly  opposite  to  each  other;  then  send  the  whole 
force  of  the  battery  through  the  vane,  entering  at 
one  end  of  it  and  going  out  at  the  other.  If  the 
metal  explodes,  I  imagine  it  will  be  found  to  make 
holes  in  the  paper,  forcing  the  torn  parts  out  on  the 
sides  opposite  to  the  metal.  A  more  expensive,  but 
perhaps  a  more  satisfactory  experiment  would  be  to 
make  a  new  vane  as  exactly  as  possible  like  that  in 
question,  in  all  the  particulars  of  its  description,  and 
place  it  on  a  tall  mast  fixed  on  some  hill  subject  to 
strokes  of  lightning,  with  a  better  conductor  to  the 
earth  than  the  wood  of  the  mast;  if  this  should  be 
struck  in  the  course  of  a  few  years,  and  the  same 
effects  appear  upon  it,  it  would  be  still  more  mirac- 
ulous to  suppose  it  happened  by  accident  to  be 
exactly  situated  where  those  crossing  threads  of 
different  electricities  were  afterwards  to  meet. 

36.  The  perforation  of  glass  bottles  when  over- 
charged is,  I  imagine,  a  different  case,  and  not  ex- 
plicable by  either  of  these  hypotheses.  I  cannot 
well  suppose  the  breach  to  be  occasioned  by  the 
passage  of  electricity  through  it;  since  a  single 
bottle,  though  so  broken  in  the  discharge,  always  is 
found  to  send  round  in  its  usual  course  the  quantity 
with  which  it  was  charged.  Then  the  breach  never 
happens  but  at  the  instant  of  the  circuitous  dis- 


1782] 


Essays 


IOI 


charge,  either  by  the  discharging  rod,  or  in  over- 
leaping the  borders  of  the  glass.  Thus,  I  have  been 
present  when  a  battery  of  twenty  glasses  was  dis- 
charged by  the  discharging  rod,  and  produced  the 
same  effect  in  its  circuit  as  if  none  of  the  bottles  had 
been  pierced;  and  yet,  on  examining  them,  we  found 
no  less  than  twelve  of  them  in  that  situation.  Now, 
all  the  bottles  of  the  battery  being  united  by  a  com- 
munication of  all  the  outsides  together,  and  of  all 
the  insides  together,  if  one  of  them  had  been  pierced 
by  a  forced  passage  of  the  different  kinds  of  electric- 
ity to  meet  each  other,  before  the  discharge  by  the 
discharging  rod,  it  would  not  only  have  prevented 
the  passage  of  the  electricity  by  the  common  circuit, 
but  it  would  have  saved  all  the  rest  of  its  fellows, 
by  conducting  the  whole  through  its  own  breach. 
And  it  is  not  easy  to  conceive  that  twelve  bottles  in 
twenty  should  be  so  equally  strong  as  to  support  the 
whole  strength  of  their  charge,  till  the  circuit  of 
their  discharge  was  opened,  and  then  be  so  equally 
weak  as  to  break  altogether  when  the  weight  of  that 
charge  was  taken  off  from  them  by  opening  the  cir- 
cuits. At  some  other  time  I  will  give  you  my 
opinion  of  this  effect,  if  you  desire  it. 

I  have  taken  the  account  of  this  stroke  of  light- 
ning from  an  Italian  .piece,  entitled  "Analisi  d'  un 
nuovo  Fenomeno  del  Fulmine,"  the  dedication  of 
which  is  subscribed  Carlo  Barletti,  delle  Scuole  Pie, 
who,  I  suppose,  is  the  author.  As  I  do  not  per- 
fectly understand  that  language,  I  may  possibly  in 
some  things  have  mistaken  that  philosopher's  mean- 
ing.   I  therefore  desire,  my  dear  friend,  that  you 


io2  Benjamin  Franklin 


would  not  permit  this  to  be  published  till  you  have 
compared  and  considered  it  with  that  original  piece, 
and  communicated  to  me  your  remarks  and  correc- 
tions. Nor  would  I  in  any  case  have  it  appear  with 
my  name,  as  perhaps  it  may  occasion  disputes,  and 
I  have  no  time  to  attend  to  them. 


XIX 


AN  ACCOUNT  OF  TOADS  FOUND  ENCLOSED  IN  SOLID 
STONE 

At  Passy,  near  Paris,  April  6,  1782,  being  with 
M.  de  Chaumont,  viewing  his  quarry,  he  mentioned 
to  me  that  the  workmen  had  found  a  living  toad 
shut  up  in  the  stone.  On  questioning  one  of  them, 
he  told  us  they  had  found  four  in  different  cells 
which  had  no  communication;  that  there  was  in 
each  cell  some  loose,  soft,  yellowish  earth,  which 
appeared  to  be  very  moist.  We  asked  if  he  could 
show  us  the  parts  of  the  stone  that  formed  the  cells. 
He  said,  No;  for  they  were  thrown  among  the  rest 
of  what  was  dug  out,  and  he  knew  not  where  to  find 
them.  We  asked  if  there  appeared  any  opening  by 
which  the  animal  could  enter.  He  said,  No.  We 
asked  if,  in  the  course  of  his  business  as  a  laborer  in 
quarries,  he  had  often  met  with  the  like.  He  said, 
Never  before.  We  asked  if  he  could  show  us  the 
toads.  He  said,  he  had  thrown  two  of  them  up  on 
a  higher  part  of  the  quarry,  but  knew  not  what 
became  of  the  others. 

He  then  came  up  to  the  place  where  he  had  thrown 
103 


104  Benjamin  Franklin  [1782 

the  two,  and,  finding  them,  he  took  them  by  the  foot 
and  threw  them  up  to  us,  upon  the  ground  where  we 
stood.  One  of  them  was  quite  dead,  and  appeared 
very  lean;  the  other  was  plump  and  still  living. 
The  part  of  the  rock  where  they  were  found  is  at 
least  fifteen  feet  below  its  surface,  and  is  a  kind  of 
limestone.  A  part  of  it  is  filled  with  ancient  sea- 
shells,  and  other  marine  substances.  If  these  ani- 
mals have  remained  in  this  confinement  since  the 
formation  of  the  rock,  they  are  probably  some  thou- 
sands of  years  old.  We  have  put  them  in  spirits  of 
wine,  to  preserve  their  bodies  a  little  longer.  The 
workmen  have  promised  to  call  us  if  they  meet  with 
any  more,  that  we  may  examine  their  situation. 
Before  a  suitable  bottle  could  be  found  to  receive 
them,  that  which  was  living  when  we  first  had  them 
appeared  to  be  quite  dead  and  motionless ;  but  being 
in  the  bottle,  and  the  spirits  poured  over  them,  he 
flounced  about  in  it  very  vigorously  for  two  or  three 
minutes,  and  then  expired. 

It  is  observed  that  animals  who  perspire  but  little 
can  live  long  without  food:  such  as  tortoises,  whose 
flesh  is  covered  with  a  thick  shell ;  and  snakes,  who 
are  covered  with  scales,  which  are  of  so  close  a  sub- 
stance as  scarcely  to  admit  the  passage  of  perspir- 
able matter  through  them.  Animals  that  have  open 
pores  all  over  the  surface  of  their  bodies,  and  live  in 
air  which  takes  off  continually  the  perspirable  part 
of  their  substance,  naturally  require  a  continual  sup- 
ply of  food  to  maintain  their  bulk.  Toads  shut  up  in 
solid  stone,  which  prevents  their  losing  any  thing  of 
their  substance,  may  perhaps  for  that  reason  need  no 


1782] 


Essays 


105 


supply;  and  being  guarded  against  all  accidents,  and 
all  the  inclemencies  of  the  air  and  changes  of  the 
seasons,  are,  it  seems,  subject  to  no  diseases,  and 
become  as  it  were  immortal.         B.  Franklin.1 

1  The  following  copy  of  a  letter  from  Sir  John  Pringle  to  Mr.  A.  Small, 
was  annexed  to  the  above  account,  in  Dr.  Franklin's  papers. — W.  T.  F. 

"Minorca,  25  April,  1780. 

"Sir: — Last  year  I  had  the  honor  to  inform  you  that  two  of  those 
large  moths  called  Muskitoe  Hawks,  which  appear  about  September, 
and  disappear  about  the  beginning  of  December,  lived  seventy-one 
days  after  I  had  cut  their  heads  off  with  a  pair  of  scissors. 

"The  last  autumn  I  made  the  same  experiment  upon  several,  keep- 
ing them  under  separate  glasses,  in  a  closet,  where  there  was  no  fire. 
The  most  of  them  lived  different  periods,  from  three  to  sixty  and 
seventy  days.  Those  which  exceeded  that  number  of  days  were  four, 
viz.,  one  from  the  30th  of  October  to  the  21st  of  January,  eighty- three 
days;  one  from  the  12th  of  December  to  the  21st  of  April,  one  hundred 
and  thirty-one  days;  and  one  from  the  24th  of  October  to  the  15th 
of  April,  one  hundred  and  seventy-four  days.  As  they  are  very 
active,  and  covered  with  a  sort  of  plumage,  which  makes  it  difficult  to 
cut  their  heads  off,  without  bruising  or  otherwise  injuring  the  body,  I 
imagine  that  may  partly  be  the  reason  of  their  living  different  periods ; 
and  if,  after  the  operation,  any  glutinous  liquor  proceeded  from  the 
body,  that  moth  would  die  soon. 

"I  put  several  under  glasses,  without  cutting  off  their  heads,  none  of 
which  lived  many  days. 

"I  am,  sir,  with  great  esteem,  your  most  obedient  and  most  humble 
servant,  John  Pringle." 


XX 


TO  l'  abbe  soulavie1 

Passy,  22  September,  1782. 

Sir; — I  return  the  papers  with  some  corrections, 
I  did  not  find  coal  mines  under  the  calcareous  rock 
in  Derbyshire.3  I  only  remarked,  that,  at  the  lowest 
part  of  that  rocky  mountain  which  was  in  sight, 
there  were  oyster  shells  mixed  in  the  stone;  and 
part  of  the  high  county  of  Derby  being  probably  as 
much  above  the  level  of  the  sea,  as  the  coal  mines 
of  Whitehaven  were  below  it,  seemed  a  proof  that 
there  had  been  a  great  bouleversement  in  the  surface 
of  that  island,  some  part  of  it  having  been  depressed 
under  the  sea,  and  other  parts,  which  had  been  under 
it,  being  raised  above  it.  Such  changes  in  the  super- 
ficial parts  of  the  globe  seemed  to  me  unlikely  to 
happen,  if  the  earth  were  solid  to  the  centre.  I 
therefore  imagined,  that  the  internal  parts  might  be 
a  fluid  more  dense,  and  of  greater  specific  gravity 
than  any  of  the  solids  we  are  acquainted  with,  which 

1  Read  at  a  meeting  of  the  American  Philosophical  Society,  Novem- 
ber 21,  1788. 

2  Occasioned  by  his  sending  me  some  notes  he  had  taken,  of  what  I 
had  said  to  him  in  conversation  on  the  Theory  of  the  Earth.  I  wrote  it 
to  set  him  right  in  some  points  wherein  he  had  mistaken  my  meaning. 
— Note  by  B.  F. 

106 


1782]  Essays  107 

therefore  might  swim  in  or  upon  that  fluid.  Thus 
the  surface  of  the  globe  would  be  a  shell,  capable  of 
being  broken  and  disordered  by  the  violent  move- 
ments of  the  fluid  on  which  it  rested.  And  as  air 
has  been  compressed  by  art,  so  as  to  be  twice  as 
dense  as  water,  in  which  case,  if  such  air  and  water 
could  be  contained  in  a  strong  glass  vessel,  the  air 
would  be  seen  to  take  the  lowest  place,  and  the 
water  to  float  above  and  upon  it;  and  as  we  know 
not  yet  the  degree  of  density  to  which  air  may  be 
compressed,  and  M.  Amontons  calculated  that,  its 
density  increasing  as  it  approached  the  centre  in 
the  same  proportion  as  above  the  surface,  it  would, 
at  the  depth  of — leagues,  be  heavier  than  gold,  p  s- 
sibly  the  dense  fluid  occupying  the  internal  parts  of 
the  globe  might  be  air  compressed.  And  as  the  force 
of  expansion  in  dense  air  when  heated  is  in  propor- 
tion to  its  density,  this  central  air  might  afford  an- 
other agent  to  move  the  surface,  as  well  as  be  of  use 
in  keeping  alive  the  subterraneous  fires;  though,  as 
you  observe,  the  sudden  rarefaction  of  water  com- 
ing into  contact  with  those  fires,  may  also  be  an 
agent  sufficiently  strong  for  that  purpose,  when  act- 
ing between  the  incumbent  earth  and  the  fluid  on 
which  it  rests. 

If  one  might  indulge  imagination,  in  supposing 
how  such  a  globe  was  formed,  I  should  conceive, 
that,  all  the  elements  in  separate  particles  being 
originally  mixed  in  confusion,  and  occupying  a  great 
space,  they  would  (as  soon  as  the  almighty  fiat  or- 
dained gravity,  or  the  mutual  attraction  of  certain 
parts,  and  the  mutual  repulsion  of  others,  to  exist) 


108  Benjamin  Franklin  [1782 

all  move  to  their  common  centre;  and  the  air  being 
a  fluid  whose  parts  repel  each  other,  though  drawn 
to  the  common  centre  by  their  gravity,  would  be 
densest  towards  the  centre,  and  rarer  as  more  re- 
mote ;  consequently  all  matters  lighter  than  the  cen- 
tral parts  of  that  air,  and  immersed  in  it,  would 
recede  from  the  centre,  and  rise  till  they  arrived 
at  that  region  of  the  air  which  was  of  the  same 
specific  gravity  with  themselves,  where  they  would 
rest ;  while  other  matter,  mixed  with  the  lighter  air, 
would  descend,  and  the  two  meeting  would  form  the 
shell  of  the  first  earth,  leaving  the  upper  atmosphere 
nearly  clear.  The  original  movement  of  the  parts 
towards  their  common  centre  would  naturally  form 
a  whirl  there,  which  would  continue  upon  the  turn- 
ing of  the  new-formed  globe  upon  its  axis,  and  the 
greatest  diameter  of  the  shell  would  be  in  its  equa- 
tor. If  by  any  accident  afterwards  the  axis  should 
be  changed,  the  dense  internal  fluid,  by  altering  its 
form,  must  burst  the  shell,  and  throw  all  its  sub- 
stance into  the  confusion  in  which  we  find  it. 

I  will  not  trouble  you  at  present  with  my  fancies 
concerning  the  manner  of  forming  the  rest  of  our 
system.  Superior  beings  smile  at  our  theories,  and 
at  our  presumption  in  making  them.  I  will  just 
mention  that  your  observation  of  the  ferruginous 
nature  of  the  lava  which  is  thrown  out  from  the 
depths  of  our  volcanoes,  gave  me  great  pleasure.  It 
has  long  been  a  supposition  of  mine  that  the  iron 
contained  in  the  surface  of  the  globe  has  made  it 
capable  of  becoming,  as  it  is,  a  great  magnet;  that 
the  fluid  of  magnetism  perhaps  exists  in  all  space; 


Essays 


109 


so  that  there  is  a  magnetical  north  and  south  of  the 
universe  as  well  as  of  this  globe,  and  that,  if  it  were 
possible  for  a  man  to  fly  from  star  to  star,  he  might 
govern  his  course  by  the  compass;  that  it  was  by 
the  power  of  this  general  magnetism  this  globe  be- 
came a  particular  magnet.  In  soft  or  hot  iron,  the 
fluid  of  magnetism  is  naturally  diffused  equally,  when 
within  the  influence  of  the  magnet  it  is  drawn  to 
one  end  of  the  iron,  made  denser  there  and  rarer  at 
the  other.  While  the  iron  continues  soft  and  hot,  it 
is  only  a  temporary  magnet ;  if  it  cools  or  grows  hard 
in  that  situation,  it  becomes  a  permanent  one,  the 
magnetic  fluid  not  easily  resuming  its  equilibrium. 
Perhaps  it  may  be  owing  to  the  permanent  magnet- 
'ism  of  this  globe,  which  it  had  not  at  first,  that  its 
axis  is  at  present  kept  parallel  to  itself,  and  not  liable 
to  the  changes  it  formerly  suffered,  which  occasioned 
the  rupture  of  its  shell,  the  submersions  and  emer- 
sions of  its  lands,  and  the  confusion  of  its  seasons. 
The  present  polar  and  equatorial  diameters  differing 
from  each  other  near  ten  leagues,  it  is  easy  to  con- 
ceive, in  case  some  power  should  shift  the  axis  gradu- 
ally, and  place  it  in  the  present  equator,  and  make 
the  new  equator  pass  through  the  present  poles, 
what  a  sinking  of  the  waters  would  happen  in 
the  present  equatorial  regions,  and  what  a  rising 
in  the  present  polar  regions;  so  that  vast  tracts 
would  be  discovered  that  now  are  under  water,  and 
others  covered  that  are  now  dry,  the  water  rising 
and  sinking  in  the  different  extremes  near  five 
leagues.  Such  an  operation  as  this  possibly  occa- 
sioned much  of  Europe,  and,  among  the  rest,  this 


no  Benjamin  Franklin  [1782 

mountain  of  Passy  on  which  I  live,  and  which  is 
composed  of  limestone,  rock,  and  sea-shells,  to  be 
abandoned  by  the  sea,  and  to  change  its  ancient 
climate,  which  seems  to  have  been  a  hot  one. 

The  globe  being  now  become  a  perfect  magnet, 
we  are,  perhaps,  safe  from  any  change  of  its  axis. 
But  we  are  still  subject  to  the  accidents  on  the  sur- 
face, which  are  occasioned  by  a  wave  in  the  internal 
ponderous  fluid;  and  such  a  wave  is  producible  by 
the  sudden  violent  explosion  you  mention,  happen- 
ing from  the  junction  of  water  and  fire  under  the 
earth,  which  not  only  lifts  the  incumbent  earth  that 
is  over  the  explosion,  but,  impressing  with  the  same 
force  the  fluid  under  it,  creates  a  wave,  that  may 
run  a  thousand  leagues  lifting,  and  thereby  shaking 
successively  all  the  countries  under  which  it  passes. 
I  know  not  whether  I  have  expressed  myself  so 
clearly  as  not  to  get  out  of  your  sight  in  these 
reveries.  If  they  occasion  any  new  inquiries,  and  pro- 
duce a  better  hypothesis,  they  will  not  be  quite  use- 
less. You  see  I  have  given  a  loose  to  imagination ; 
but  I  approve  much  more  your  method  of  philo- 
sophizing, which  proceeds  upon  actual  observation, 
makes  a  collection  of  facts,  and  concludes  no  further 
than  those  facts  will  warrant.  In  my  present  circum- 
stances, that  mode  of  studying  the  nature  of  the  globe 
is  out  of  my  power,  and  therefore  I  have  permitted 
myself  to  wander  a  little  in  the  wilds  of  fancy. 
With  great  esteem,  I  have  the  honor  to  be,  sir,  etc., 

B.  Franklin. 

P.  S. — I  have  heard  that  chemists  can  by  their  art 
decompose  stone  and  wood,  extracting  a  consider- 


1782] 


Essays 


in 


able  quantity  of  water  from  the  one  and  air  from 
the  other.  It  seems  natural  to  conclude,  from  this, 
that  water  and  air  were  ingredients  in  their  original 
composition;  for  men  cannot  make  new  matter  of 
any  kind.  In  the  same  manner  may  we  not  suppose 
that,  when  we  consume  combustibles  of  all  kinds, 
and  produce  heat  or  light,  we  do  not  create  that  heat 
or  light,  but  only  decompose  a  substance  which 
received  it  originally  as  a  part  of  its  composition? 
Heat  may  be  thus  considered  as  originally  in  a  fluid 
state;  but,  attracted  by  organized  bodies  in  their 
growth,  becomes  a  part  of  the  solid.  Besides  this, 
I  can  conceive  that  in  the  first  assemblage  of  the 
particles  of  which  this  earth  is  composed,  each 
brought  its  portion  of  the  loose  heat  that  had  been 
connected  with  it,  and  the  whole,  when  pressed  to- 
gether, produced  the  internal  fire  that  still  subsists. 


XXI 


PROPOSITIONS   RELATIVE  TO   PRIVATEERING  COMMU- 
NICATED TO  MR.  OSWALD1 

It  is  for  the  interest  of  humanity  in  general  that 
the  occasions  of  war  and  the  inducements  to  it  should 
be  diminished. 

If  rapine  is  abolished,  one  of  the  encouragements 
to  war  is  taken  away,  and  peace  therefore  more  likely 
to  continue  and  be  lasting. 

The  practice  of  robbing  merchants  on  the  high 
seas,  a  remnant  of  the  ancient  piracy,  though  it  may 
be  accidentally  beneficial  to  particular  persons,  is  far 
from  being  profitable  to  all  engaged  in  it,  or  to  the 
nation  that  authorizes  it.  In  the  beginning  of  a  war, 
some  rich  ships,  not  upon  their  guard,  are  surprised 
and  taken.  This  encourages  the  first  adventurers  to 
fit  out  more  armed  vessels,  and  many  others  to  do 
the  same.  But  the  enemy  at  the  same  time  become 
more  careful,  arm  their  merchant  ships  better,  and 
render  them  not  so  easy  to  be  taken;  they  go  also 
more  under  protection  of  convoys;  thus,  while  the 

1  These  propositions  are  the  same  in  substance  as  the  author's  two 
papers  entitled,  A  Thought  concerning  the  Sugar  Islands,  and  Obser- 
vations on  War. 


112 


Essays 


113 


privateers  to  take  them  are  multiplied,  the  vessels 
subject  to  be  taken,  and  the  chances  of  profit,  are 
diminished,  so  that  many  cruises  are  made  wherein 
the  expenses  overgo  the  gains ;  and,  as  is  the  case  in 
other  lotteries,  though  particulars  have  got  prizes, 
the  mass  of  adventurers  are  losers,  the  whole  expense 
of  fitting  out  all  the  privateers,  during  a  war,  being 
much  greater  than  the  whole  amount  of  goods  taken. 
Then  there  is  the  national  loss  of  all  the  labor  of  so 
many  men  during  the  time  they  have  been  employed 
in  robbing;  who,  besides,  spend  what  they  get  in 
riot,  drunkenness,  and  debauchery,  lose  their  habits 
of  industry,  are  rarely  fit  for  any  sober  business  after 
a  peace,  and  serve  only  to  increase  the  number  of 
highwaymen  and  housebreakers.  Even  the  under- 
takers, who  have  been  fortunate,  are  by  sudden 
wealth  led  into  expensive  living,  the  habit  of  which 
continues  when  the  means  of  supporting  it  ceases, 
and  finally  ruins  them;  a  just  punishment  for  their 
having  wantonly  and  unfeelingly  ruined  many  hon- 
est, innocent  traders  and  their  families,  whose 
subsistence  was  employed  in  serving  the  common 
interests  of  mankind. 

Should  it  be  agreed  and  become  a  part  of  the  law 
of  nations,  that  the  cultivators  of  the  earth  are  not 
to  be  molested  or  interrupted  in  their  peaceable  and 
useful  employment,  the  inhabitants  of  the  sugar 
islands  would  perhaps  come  under  the  protection  of 
such  a  regulation,  which  would  be  a  great  advantage 
to  the  nations  who  at  present  hold  those  islands, 
since  the  cost  of  sugar  to  the  consumer  in  those 
nations  consists  not  merely  in  the  price  he  pays  for 


ii4  Benjamin  Franklin  [1783 

it  by  the  pound,  but  in  the  accumulated  charge  of 
all  the  taxes  he  pays  in  every  war,  to  fit  out  fleets 
and  maintain  troops  for  the  defence  of  the  islands 
that  raise  the  sugar,  and  the  ships  that  bring  it  home. 
But  the  expense  of  treasure  is  not  all.  A  celebrated 
philosophical  writer  remarks  that,  when  he  con- 
sidered the  wars  made  in  Africa,  for  prisoners  to 
raise  sugars  in  America,  the  numbers  slain  in  those 
wars,  the  numbers  that,  being  crowded  in  ships, 
perish  in  the  transportation,  and  the  numbers  that 
die  under  the  severities  of  slavery,  he  could  scarce  look 
on  a  morsel  of  sugar  without  conceiving  it  spotted 
with  human  blood.  If  he  had  considered  also  the 
blood  of  one  another,  which  the  white  nations  shed 
in  fighting  for  those  islands,  he  would  have  imagined 
his  sugar  not  as  spotted  only,  but  as  thoroughly 
dyed  red.  On  these  accounts  I  am  persuaded  that 
the  subjects  of  the  Emperor  of  Germany,  and  the 
Empress  of  Russia,  who  have  no  sugar  islands,  con- 
sume sugar  cheaper  at  Vienna  and  Moscow,  with  all 
the  charge  of  transporting  it  after  its  arrival  in 
Europe  than  the  citizens  of  London  or  of  Paris. 
And  I  sincerely  believe  that  if  France  and  England 
were  to  decide,  by  throwing  dice,  which  should  have 
the  whole  of  their  sugar  islands,  the  loser  in  the 
throw  would  be  the  gainer.  The  future  expense  of 
defending  them  would  be  saved:  the  sugars  would 
be  bought  cheaper  by  all  Europe,  if  the  inhabitants 
might  make  it  without  interruption,  and,  whoever 
imported  the  sugar,  the  same  revenue  might  be 
raised  by  duties  at  the  custom-houses  of  the  nation 
that  consumed  it.    And,  on  the  whole,  I  conceive 


1783] 


Essays 


115 


it  would,  be  better  for  the  nations  now  possessing 
sugar  colonies  to  give  up  their  claim  to  them;  let 
them  govern  themselves,  and  put  them  under  the 
protection  of  all  the  powers  of  Europe  as  neutral 
countries,  open  to  the  commerce  of  all,  the  profits 
of  the  present  monopolies  being  by  no  means  equiva- 
lent to  the  expense  of  maintaining  them. 

Article 

If  war  should  hereafter  arise  between  Great  Britain 
and  the  United  States,  which  God  forbid,  the  mer- 
chants of  either  country  then  residing  in  the  other 
shall  be  allowed  to  remain  nine  months  to  collect 
their  debts  and  settle  their  affairs,  and  may  depart 
freely,  carrying  off  all  their  effects  without  molesta- 
tion or  hindrance.  And  all  fishermen,  all  cultivators 
of  the  earth,  and  all  artisans  or  manufacturers  un- 
armed, and  inhabiting  unfortified  towns,  villages,  or 
places,  who  labor  for  the  common  subsistence  and 
benefit  of  mankind,  and  peaceably  follow  their 
respective  employments,  shall  be  allowed  to  con- 
tinue the  same,  and  shall  not  be  molested  by  the 
armed  force  of  the  enemy  in  whose  power  by  the 
events  of  the  war  they  may  happen  to  fall;  but,  if 
any  thing  is  necessary  to  be  taken  from  them,  for  the 
use  of  such  armed  force,  the  same  shall  be  paid  for  at 
a  reasonable  price.  And  all  merchants  or  traders 
with  their  unarmed  vessels,  employed  in  commerce, 
exchanging  the  products  of  different  places,  and 
thereby  rendering  the  necessaries,  conveniences,  and 
comforts  of  human  life  more  easy  to  obtain  and  more 
general,  shall  be  allowed  to  pass  freely,  unmolested. 


n6  Benjamin  Franklin  [1783 

And  neither  of  the  powers,  parties  to  this  treaty, 
shall  grant  or  issue  any  commission  to  any  private 
armed  vessels,  empowering  them  to  take  or  destroy 
such  trading  ships,  or  interrupt  such  commerce. 


XXII 


TO  SIR  JOSEPH  BANKS 

Passy,  i  December,  1783. 

Dear  Sir: — In  mine  of  yesterday  I  promised  to 
give  you  an  account  of  Messrs.  Charles  &  Robert's 
experiment,  which  was  to  have  been  made  this  day, 
and  at  which  I  intended  to  be  present.  Being  a  little 
indisposed,  and  the  air  cool,  and  the  ground  damp,  I 
declined  going  into  the  garden  of  the  Tuileries, 
where  the  balloon  was  placed,  not  knowing  how  long 
I  might  be  obliged  to  wait  there  before  it  was  ready 
to  depart,  and  chose  to  stay  in  my  carriage  near  the 
statue  of  Louis  XV.,  from  whence  I  could  well  see  it 
rise,  and  have  an  extensive  view  of  the  region  of  air 
through  which,  as  the  wind  sat,  it  was  likely  to  pass. 
The  morning  was  foggy,  but  about  one  o'clock  the  air 
became  tolerably  clear,  to  the  great  satisfaction  of  the 
spectators,  who  were  infinite,  notice  having  been 
given  of  the  intended  experiment  several  days  before 
in  the  papers,  so  that  all  Paris  was  out,  either  about 
the  Tuileries,  on  the  quays  and  bridges,  in  the  fields, 
the  streets,  at  the  windows,  or  on  the  tops  of  houses, 
besides  the  inhabitants  of  all  the  towns  and  villages 
of  the  environs.  Never  before  was  a  philosophical 
experiment  so  magnificently  attended.  Some  guns 
117 


n8  Benjamin  Franklin  [1783 

were  fired  to  give  notice  that  the  departure  of  the 
great  balloon  was  near,  and  a  small  one  was  dis- 
charged, which  went  to  an  amazing  height,  there 
being  but  little  wind  to  make  it  deviate  from  its  per- 
pendicular course,  and  at  length  the  sight  of  it  was 
lost.  Means  were  used,  I  am  told,  to  prevent  the 
great  balloon's  rising  so  high  as  might  endanger  its 
bursting.  Several  bags  of  sand  were  taken  on  board 
before  the  cord  that  held  it  down  was  cut,  and  the 
whole  weight  being  then  too  much  to  be  lifted,  such 
a  quantity  was  discharged  as  to  permit  its  rising 
slowly.  Thus  it  would  sooner  arrive  at  that  region 
where  it  would  be  in  equilibrio  with  the  surround- 
ing air,  and  by  discharging  more  sand  afterwards,  it 
might  go  higher  if  desired.  Between  one  and  two 
o'clock,  all  eyes  were  gratified  with  seeing  it  rise  ma- 
jestically from  among  the  trees,  and  ascend  gradu- 
ally above  the  buildings,  a  most  beautiful  spectacle. 
When  it  was  about  two  hundred  feet  high,  the  brave 
adventurers  held  out  and  waved  a  little  white  pen- 
nant, on  both  sides  their  car,  to  salute  the  spectators, 
who  returned  loud  claps  of  applause.  The  wind  was 
very  little,  so  that  the  object,  though  moving  to  the 
northward,  continued  long  in  view;  and  it  was  a 
great  while  before  the  admiring  people  began  to  dis- 
perse. The  persons  embarked  were  Mr.  Charles, 
professor  of  experimental  philosophy,  and  a  zealous 
promoter  of  that  science;  and  one  of  the  Messieurs 
Robert,  the  very  ingenious  constructors  of  the  ma- 
chine. When  it  arrived  at  its  height,  which  I  sup- 
pose might  be  three  hundred  or  four  hundred  toises, 
it  appeared  to  have  only  horizontal  motion.    I  had  a 


Essays  119 


pocket-glass,  with  which  I  followed  it,  till  I  lost  sight, 
first  of  the  men,  then  of  the  car,  and  when  I  last  saw 
the  balloon,  it  appeared  no  bigger  than  a  walnut.  I 
write  this  at  seven  in  the  evening.  What  became 
of  them  is  not  yet  known  here.  I  hope  they  de- 
scended by  daylight,  so  as  to  see  and  avoid  falling 
among  trees  or  on  houses,  and  that  the  experiment 
Was  completed  without  any  mischievous  accident, 
which  the  novelty  of  it  and  the  want  of  experience 
might  well  occasion.  I  am  the  more  anxious  for  the 
event,  because  I  am  not  well  informed  of  the  means 
provided  for  letting  themselves  gently  down,  and  the 
loss  of  these  very  ingenious  men  would  not  only  be  a 
discouragement  to  the  progress  of  the  art,  but  be 
a  sensible  loss  to  science  and  society. 

I  shall  enclose  one  of  the  tickets  of  admission,  on 
which  the  globe  was  represented,  as  originally  in- 
tended, but  is  altered  by  the  pen  to  show  its  real 
state  when  it  went  off.  When  the  tickets  were  en- 
graved the  car  was  to  have  been  hung  to  the  neck  of 
the  globe,  as  represented  by  a  little  drawing  I  have 
made  in  the  corner  A.1 

I  suppose  it  may  have  been  an  apprehension  of 
danger  in  straining  too  much  the  balloon  or  tearing 
the  silk,  that  induced  the  constructors  to  throw  a  net 
over  it,  fixed  to  a  hoop  which  went  round  its  middle, 
and  to  hang  the  car  to  that  hoop,  as  you  see  in  Fig.  B. 

Tuesday  morning,  December  2d. — I  am  relieved 
from  my  anxiety  by  hearing  that  the  adventurers  de- 
scended well  near  l'lsle  Adam  before  sunset.  This 

1  The  copy  of  this  letter  that  has  fallen  into  our  hands  does  not  give 
the  drawings  here  referred  to. 


120  Benjamin  Franklin  [1783 

place  is  near  seven  leagues  from  Paris.  Had  the 
wind  blown  fresh  they  might  have  gone  much  farther. 

If  I  receive  any  further  particulars  of  importance, 
I  shall  communicate  them  hereafter. 

With  great  esteem,  I  am,  dear  sir,  your  most 
obedient  and  most  humble  servant, 

B.  Franklin. 

P.  S.  Tuesday  evening. — Since  writing  the  above 
I  have  received  the  printed  paper  and  the  manuscript 
containing  some  particulars  of  the  experiment,  which 
I  enclose.  I  hear  further  that  the  travellers  had  per- 
fect command  of  their  carriage,  descending  as  they 
pleased  by  letting  some  of  the  inflammable  air  es- 
cape, and  rising  again  by  discharging  some  sand; 
that  they  descended  over  a  field  so  low  as  to  talk 
with  the  laborers  in  passing,  and  mounted  again  to 
pass  a  hill.  The  little  balloon  falling  at  Vincennes 
shows  that  mounting  higher  it  met  with  a  current  of 
air  in  a  contrary  direction,  an  observation  that  may 
be  of  use  to  future  aerial  voyagers. 


XXIII 


METEOROLOGICAL  IMAGINATIONS  AND  CONJECTURES  1 

Passy,  May,  1784. 

There  seems  to  be  a  region  high  in  the  air  over 
all  countries,  where  it  is  always  winter,  where  frost 
exists  continually,  since  in  the  midst  of  summer,  on 
the  surface  of  the  earth,  ice  falls  often  from  above  in 
the  form  of  hail. 

Hailstones  of  the  great  weight  we  sometimes  find 
them  did  not  probably  acquire  their  magnitude  before 
they  began  to  descend.  The  air  being  eight  hundred 
times  rarer  than  water,  is  unable  to  support  it  but  in 
the  shape  of  vapor,  a  state  in  which  its  particles  are 
separated.  As  soon  as  they  are  condensed  by  the 
cold  of  the  upper  region,  so  as  to  form  a  drop,  that 
drop  begins  to  fall.  If  it  freezes  into  a  grain  of  ice, 
that  ice  descends.  In  descending,  both  the  drop  of 
water  and  the  grain  of  ice  are  augmented  by  par- 
ticles of  the  vapor  they  pass  through  in  falling,  and 
which  they  -  condense  by  coldness,  and  attach  to 
themselves. 

It  is  possible  that  in  summer  much  of  what  is  rain 
when  it  arrives  at  the  surface  of  the  earth,  might 

1  First  printed  in  the  Memoirs  of  the  Literary  and  Philosophical  Society 
of  Manchester,  Vol.  II.,  p.  357.  It  was  communicated  to  the  society  by 
Dr.  Percival,  and  read  December  22,  1784. 

121 


122  Benjamin  Franklin  [1784 

have  been  snow  when  it  began  its  descent,  but  being 
thawed  in  passing  through  the  warm  air  near  the 
surface,  it  is  changed  from  snow  into  rain. 

How  immensely  cold  must  be  the  original  particle 
of  hail  which  forms  the  centre  of  the  future  hailstone, 
since  it  is  capable  of  communicating  sufficient  cold,  if 
I  may  so  speak,  to  freeze  all  the  mass  of  vapor  con- 
densed round  it,  and  form  a  lump  of  perhaps  six  or 
eight  ounces  in  weight! 

When  in  summer-time  the  sun  is  high,  and  contin- 
ues long  every  day  above  the  horizon,  his  rays  strike 
the  earth  more  directly,  and  with  longer  continuance, 
than  in  the  winter ;  hence  the  surface  is  more  heated, 
and  to  a  greater  depth,  by  the  effect  of  those  rays. 

When  rain  falls  on  the  heated  earth,  and  soaks 
down  into  it,  it  carries  down  with  it  a  great  part  of 
the  heat,  which  by  that  means  descends  still  deeper. 

The  mass  of  earth,  to  the  depth  perhaps  of  thirty 
feet,  being  thus  heated  to  a  certain  degree,  continues 
to  retain  its  heat  for  some  time.  Thus  the  first 
snows  that  fall  in  the  beginning  of  winter  seldom  lie 
long  on  the  surface,  but  are  soon  melted,  and  soon 
absorbed.  After  which  the  winds  that  blow  over  the 
country  on  which  the  snows  had  fallen,  are  not  ren- 
dered so  cold  as  they  would  have  been  by  those 
snows  if  they  had  remained,  and  thus  the  approach  of 
the  severity  of  winter  is  retarded,  and  the  extreme 
degree  of  its  cold  is  not  always  at  the  time  we  expect 
it,  viz. :  when  the  sun  is  at  its  greatest  distance  and 
the  day  shortest,  but  some  time  after  that  period, 
according  to  the  English  proverb,  which  says:  "As 


1784] 


Essays 


123 


the  day  lengthens  the  cold  strengthens,"  the  causes 
of  refrigeration  continuing  to  operate,  while  the  sun 
returns  too  slowly  and  his  force  continues  too  weak 
to  counteract  them. 

During  several  of  the  summer  months  of  the  year 
1783,  when  the  effects  of  the  sun's  rays  to  heat  the 
earth  in  these  northern  regions  should  have  been  the 
greatest,  there  existed  a  constant  fog  over  all  Europe 
and  great  part  of  North  America.  This  fog  was  of 
a  permanent  nature ;  it  was  dry,  and  the  rays  of  the 
sun  seemed  to  have  little  effect  towards  dissipating 
it,  as  they  easily  do  a  moist  fog  arising  from  water. 
They  were  indeed  rendered  so  faint  in  passing 
through  it,  that  when  collected  in  the  focus  of  a 
burning-glass  they  would  scarce  kindle  brown  paper. 
Of  course  their  summer  effect  in  heating  the  earth 
was  exceedingly  diminished. 

Hence  the  surface  was  easily  frozen. 

Hence  the  first  snows  remained  on  it  unmelted, 
and  received  continual  additions. 

Hence  perhaps  the  winter  of  1783-4  was  more 
severe  than  any  that  had  happened  for  many  years. 

The  cause  of  this  universal  fog  is  not  yet  ascer- 
tained. Whether  it  was  adventitious  to  this  earth, 
and  merely  a  smoke  proceeding  from  the  consump- 
tion by  fire  of  some  of  those  great  burning  balls  or 
globes  which  we  happen  to  meet  with  in  our  rapid 
course  round  the  sun,  and  which  are  sometimes  seen 
to  kindle  and  be  destroyed  in  passing  our  atmos- 
phere, and  whose  smoke  might  be  attracted  and  re- 
tained by  our  earth;  or  whether  it  was  the  vast 


I24 


Benjamin  Franklin 


[1784 


quantity  of  smoke,  long  continuing  to  issue  during  the 
summer  from  Hecla,  in  Iceland,  and  that  other  vol- 
cano which  arose  out  of  the  sea  near  that  island, 
which  smoke  might  be  spread  by  various  winds  over 
the  northern  part  of  the  world,  is  yet  uncertain. 

It  seems,  however,  worth  the  inquiry,  whether 
other  hard  winters  recorded  in  history  were  preceded 
by  similar  permanent  and  widely  extended  summer 
fogs.  Because,  if  found  to  be  so,  men  might  from 
such  fogs  conjecture  the  probability  of  a  succeeding 
hard  winter,  and  of  the  damage  to  be  expected  by 
the  breaking  up  of  frozen  rivers  in  the  spring,  and 
take  such  measures  as  are  possible  and  practicable 
to  secure  themselves  and  effects  from  the  mischief 
that  attended  the  last. 


XXIV 


TO  DAVID  RITTENHOUSE 

Passy,  25  June,  1784. 

Universal  space,  as  far  as  we  know  of  it,  seems  to 
be  filled  with  a  subtile  fluid,  whose  motion,  or  vibra- 
tion, is  called  light. 

This  fluid  may  possibly  be  the  same  with  that 
which,  being  attracted  by  and  entering  into  other 
more  solid  matter,  dilates  the  substance  by  separat- 
ing the  constituent  particles,  and  so  rendering  some 
solids  fluids,  and  maintaining  the  fluidity  of  others ; 
of  which  fluid  when  our  bodies  are  totally  deprived, 
they  are  said  to  be  frozen ;  when  they  have  a  proper 
quantity,  they  are  in  health  and  fit  to  perform  all 
their  functions ;  it  is  then  called  natural  heat ;  when 
too  much,  it  is  called  fever;  and  when  forced  into 
the  body  in  too  great  a  quantity  from  without,  it 
gives  pain  by  separating  and  destroying  the  flesh, 
and  is  then  called  burning,  and  the  fluid  so  entering 
and  acting  is  called  fire. 

While  organized  bodies,  animal  or  vegetable,  are 
augmenting  in  growth,  or  are  supplying  their  con- 
tinual waste,  is  not  this  done  by  attracting  and  con- 
solidating this  fluid  called  fire,  so  as  to  form  of  it  a 
125 


126 


Benjamin  Franklin 


[1784 


part  of  their  substance;  and  is  it  not  a  separation  of 
the  parts  of  such  substance,  which,  dissolving  its 
solid  state,  sets  that  subtile  fluid  at  liberty,  when  it 
again  makes  its  appearance  as  fire? 

For  the  power  of  man  relative  to  matter  seems 
limited  to  the  dividing  it,  or  mixing  the  various 
kinds  of  it,  or  changing  its  form  and  appearance  by 
different  compositions  of  it,  but  does  not  extend  to 
the  making  or  creating  of  new  matter,  or  annihilating 
the  old.  Thus,  if  fire  be  an  original  element,  or  kind 
of  matter,  its  quantity  is  fixed  and  permanent  in  the 
world.  We  cannot  destroy  any  part  of  it,  or  make 
addition  to  it;  we  can  only  separate  it  from  that 
which  confines  it,  and  so  set  it  at  liberty,  as  when  we 
put  wood  in  a  situation  to  be  burnt;  or  transfer  it 
from  one  solid  to  another,  as  when  we  make  lime  by 
burning  stone,  a  part  of  the  fire  dislodged  from  the 
wood  being  left  in  the  stone.  May  not  this  fluid, 
when  at  liberty,  be  capable  of  penetrating  and  enter- 
ing into  all  bodies,  organized  or  not,  quitting  easily 
in  totality  those  not  organized;  and  quitting  easily 
in  part  those  which  are ;  the  part  assumed  and  fixed 
remaining  till  the  body  is  dissolved  ? 

Is  it  not  this  fluid  which  keeps  asunder  the  par- 
ticles of  air,  permitting  them  to  approach,  or  sepa- 
rating them  more,  in  proportion  as  its  quantity  is 
diminished  or  augmented?  Is  it  not  the  greater 
gravity  of  the  particles  of  air,  which  forces  the  par- 
ticles of  this  fluid  to  mount  with  the  matters  to  which 
it  is  attached,  as  smoke  or  vapor? 

Does  it  not  seem  to  have  a  great  affinity  with 
water,  since  it  will  quit  a  solid  to  unite  with  that 


1784] 


Essays 


127 


fluid,  and  go  off  with  it  in  vapor,  leaving  the  solid 
cold  to  the  touch,  and  the  degree  measurable  by  the 
thermometer? 

The  vapor  rises  attached  to  this  fluid,  but  at  a 
certain  height  they  separate,  and  the  vapor  descends 
in  rain,  retaining  but  little  of  it,  in  snow  or  hail  less. 
What  becomes  of  that  fluid?  Does  it  rise  above  our 
atmosphere  and  mix  equally  with  the  universal  mass 
of  the  same  kind?  Or  does  a  spherical  stratum  of 
it,  denser,  or  less  mixed  with  air,  attracted  by  this 
globe,  and  repelled  or  pushed  up  only  to  a  certain 
height  from  its  surface,  by  the  greater  weight  of  air, 
remain  there,  surrounding  the  globe,  and  proceeding 
with  it  round  the  sun? 

In  such  case,  as  there  may  be  a  continuity  or  com- 
munication of  this  fluid  through  the  air  quite  down 
to  the  earth,  is  it  not  by  the  vibrations  given  to  it 
by  the  sun  that  light  appears  to  us ;  and  may  it  not 
be  that  every  one  of  the  infinitely  small  vibrations, 
striking  common  matter  with  a  certain  force,  enters 
its  substance,  is  held  there  by  attraction,  and  aug- 
mented by  succeeding  vibrations,  till  the  matter  has 
received  as  much  as  their  force  can  drive  into  it? 

Is  it  not  thus  that  the  surface  of  this  globe  is  con- 
tinually heated  by  such  repeated  vibrations  in  the 
day,  and  cooled  by  the  escape  of  the  heat,  when  those 
vibrations  are  discontinued  in  the  night,  or  inter- 
cepted and  reflected  by  clouds  ? 

Is  it  not  thus  that  fire  is  amassed,  and  makes  the 
greatest  part  of  the  substance  of  combustible  bodies? 

Perhaps  when  this  globe  was  first  formed  and  its 
original  particles  took  their  place  at  certain  distances 


128  Benjamin  Franklin  [1784 

from  the  centre,  in  proportion  to  their  greater  or  less 
gravity,  the  fluid  fire,  attracted  towards  that  centre, 
might  in  great  part  be  obliged,  as  lightest,  to  take 
place  above  the  rest,  and  thus  form  the  sphere  of  fire 
above  supposed,  which  would  afterwards  be  con- 
tinually diminishing  by  the  substance  it  afforded  to 
organized  bodies,  and  the  quantity  restored  to  it 
again  by  the  burning  or  other  separating  of  the 
parts  of  those  bodies. 

Is  not  the  natural  heat  of  animals  thus  produced, 
by  separating  in  digestion  the  parts  of  food  and  set- 
ting their  fire  at  liberty? 

Is  it  not  this  sphere  of  fire  which  kindles  the  wan- 
dering globes  that  sometimes  pass  through  it  in  our 
course  round  the  sun,  have  their  surface  kindled  by 
it,  and  burst  when  their  included  air  is  greatly  rare- 
fied by  the  heat  on  their  burning  surfaces? 1 

1  This  paper  was  read  before  the  American  Philosophical  Society, 
June  20,  1788,  as  a  letter  to  David  Rittenhouse,  with  the  addition 
only  of  the  following  sentence,  viz. :  "May  it  not  have  been  from  such 
considerations,  that  the  ancient  philosophers  supposed  a  sphere  of  fire 
to  exist  above  the  air  of  our  atmosphere?" 


XXV 


TO  DAVID  LE  ROY  x 

At  Sea,  on  Board  the  London  Packet, 
Captain  Truxtun,  August,  1785. 

Sir: — Your  learned  writings  on  the  navigation  of 
the  ancients,  which  contain  a  great  deal  of  curious 
information,  and  your  very  ingenious  contrivances 
for  improving  the  modern  sails  (voilure),  of  which  I 
saw  with  great  pleasure  a  successful  trial  on  the  river 
Seine,  have  induced  me  to  submit  to  your  considera- 
tion and  judgment,  some  thoughts  I  have  had  on  the 
latter  subject. 

Those  mathematicians,  who  have  endeavored  to 
improve  the  swiftness  of  vessels  by  calculating  to 
find  the  form  of  least  resistance,  seem  to  have  con- 
sidered a  ship  as  a  body  moving  through  one  fluid 
only,  the  water;  and  to  have  given  little  attention 
to  the  circumstance  of  her  moving  through  another 
fluid,  the  air.  It  is  true,  that,  when  a  vessel  sails 
right  before  the  wind,  this  circumstance  is  of  no  im- 
portance, because  the  wind  goes  with  her;  but,  in 
every  deviation  from  that  course,  the  resistance  of 

1  Read  at  a  meeting  of  the  American  Philosophical  Society,  Dec.  2, 
1785- 

129 


130  Benjamin  Franklin  [i7s5 

the  air  is  something,  and  becomes  greater  in  propor- 
tion as  that  deviation  increases.  I  waive  at  present 
the  consideration  of  those  different  degrees  of  re- 
sistance given  by  the  air  to  that  part  of  the  hull 
which  is  above  water,  and  confine  myself  to  that 
given  to  the  sails;  for  their  motion  through  the  air 
is  resisted  by  the  air,  as  the  motion  of  the  hull 
through  the  water  is  resisted  by  the  water,  though 
with  less  force  as  the  air  is  a  lighter  fluid.  And,  to 
simplify  the  discussion  as  much  as  possible,  I  would 
state  one  situation  only,  to  wit,  that  of  the  wind 
upon  the  beam,  the  ship's  course  being  directly 
across  the  wind;  and  I  would  suppose  the  sail  set 
in  an  angle  of  forty-five  degrees  with  the  keel,  as  in 
the  following  figure;  wherein  (Plate  I.,  Fig.  i), 
A  B  represents  the  body  of  the  vessel,  C  D  the  posi- 
tion of  the  sail,  E  E  E  the  direction  of  the  wind, 
M  M  the  line  of  motion.  In  observing  this  figure 
it  will  appear  that  so  much  of  the  body  of  the  vessel 
as  is  immersed  in  the  water  must,  to  go  forward, 
remove  out  of  its  way  what  water  it  meets  with  be- 
tween the  pricked  lines  F  F.  And  the  sail,  to  go 
forward,  must  move  out  of  its  way  all  the  air  its 
whole  dimension  meets  with  between  the  pricked 
lines  C  G  and  D  G.  Thus  both  the  fluids  give  re- 
sistance to  the  motion,  each  in  proportion  to  the 
quantity  of  matter  contained  in  the  dimension  to 
be  removed.  And,  though  the  air  is  vastly  lighter 
than  the  water,  and  therefore  more  easily  removed, 
yet,  the  dimension  being  much  greater,  its  effect  is 
very  considerable. 


1785]  Essays  131 

It  is  true  that,  in  the  case  stated,  the  resistance 
given  by  the  air  between  those  lines  to  the  motion  of 
the  sail  is  not  apparent  to  the  eye,  because  the 
greater  force  of  the  wind,  which  strikes  it  in  the 
direction  E  E  E,  overpowers  its  effect,  and  keeps 
the  sail  full  in  the  curve  a,  a,  a,  a,  a.  But  suppose 
the  wind  to  cease,  and  the  vessel  in  a  calm  to  be 
impelled  with  the  same  swiftness  by  oars,  the  sail 
would  then  appear  filled  in  the  contrary  curve  b,  b,  b, 
b,  b,  when  prudent  men  would  immediately  perceive, 
that  the  air  resisted  its  motion,  and  would  order  it 
to  be  taken  in. 

Is  there  any  possible  means  of  diminishing  this 
resistance,  while  the  same  quantity  of  sail  is  exposed 
to  the  action  of  the  wind,  and  therefore  the  same 
force  obtained  from  it  ?  I  think  there  is,  and  that  it 
may  be  done  by  dividing  the  sail  into  a  number  of 
parts,  and  placing  those  parts  in  a  line  one  behind 
the  other ;  thus  instead  of  one  sail  extending  from  C 
to  D,  figure  2,  if  four  sails,  containing  together  the 
same  quantity  of  canvas,  were  placed  as  in  figure  3, 
each  having  one  quarter  of  the  dimensions  of  the 
great  sail,  and  exposing  a  quarter  of  its  surface 
to  the  wind,  would  give  a  quarter  of  the  force;  so 
that  the  whole  force  obtained  from  the  wind  would 
be  the  same,  while  the  resistance  from  the  air 
would  be  nearly  reduced  to  the  space  between 
the  pricked  lines  a  b  and  c  d,  before  the  foremost 
sail. 

It  may  perhaps  be  doubted  whether  the  resistance 
from  the  air  would  be  so  diminished;  since  possibly 


132  Benjamin  Franklin  [iysg 

each  of  the  following  small  sails  having  also  air  before 
it,  which  must  be  removed,  the  resistance  on  the 
whole  would  be  the  same. 

This  is  then  a  matter  to  be  determined  by  experi- 
ment. I  will  mention  one,  that  I  many  years  since 
made  with  success  for  another  purpose;  and  I  will 
propose  another  small  one  easily  made.  If  that  too 
succeeds,  I  should  think  it  worth  while  to  make  a 
larger,  though  at  some  expense,  on  a  river  boat ;  and 
perhaps  time,  and  the  improvements  experience  will 
afford,  may  make  it  applicable  with  advantage  to 
larger  vessels. 

Having  near  my  kitchen  chimney  a  round  hole  of 
eight  inches  diameter,  through  which  was  a  strong 
steady  current  of  air,  increasing  or  diminishing  only 
as  the  fire  increased  or  diminished,  I  contrived  to 
place  my  jack  so  as  to  receive  that  current;  and, 
taking  off  the  fliers,  I  fixed  in  their  stead  on  the  same 
pivot  a  round  tin  plate  of  nearly  the  same  diameter 
with  the  hole ;  and  having  cut  it  in  radial  lines  almost 
to  the  centre,  so  as  to  have  six  equal  vanes,  I  gave 
to  each  of  them  the  obliquity  of  forty-five  degrees. 
They  moved  round,  without  the  weight,  by  the  im- 
pression only  of  the  current  of  air,  but  too  slowly  for 
the  purpose  of  roasting.  I  suspected  that  the  air 
struck  by  the  back  of  each  vane  might  possibly  by 
its  resistance  retard  the  motion;  and  to  try  this,  I 
cut  each  of  them  into  two,  and  I  placed  the  twelve, 
each  having  the  same  obliquity,  in  a  line  behind  each 
other,  when  I  perceived  a  great  augmentation  in  its 
velocity,  which  encouraged  me  to  divide  them 


1785] 


Essays 


133 


once  more,  and,  continuing  the  same  obliquity,  I 
placed  the  twenty-four  behind  each  other  in  a  line, 
when  the  force  of  the  wind  being  the  same,  and  the 
surface  of  vane  the  same,  they  moved  round  with 
much  greater  rapidity,  and  perfectly  answered  my 
purpose. 

The  second  experiment  that  I  propose  is,  to  take 
two  playing  cards  of  the  same  dimensions,  and  cut  one 
of  them  transversely  into  eight  equal  pieces;  then 
with  a  needle  string  them  upon  two  threads,  on:  near 
each  end,  and  place  them  so  upon  the  threads  that, 
when  hung  up,  they  may  be  exactly  one  over  the 
other,  at  a  distance  equal  to  their  breadth,  each  in 
a  horizontal  position;  and  let  a  small  weight,  such 
as  a  bird-shot,  be  hung  under  them,  to  make  them 
fall  in  a  straight  line  when  let  loose.  Suspend  also 
the  whole  card  by  threads  from  its  four  corners,  and 
hang  to  it  an  equal  weight,  so  as  to  draw  it  down- 
wards when  let  fall,  its  whole  breadth  pressing 
against  the  air.  Let  those  two  bodies  be  attached, 
one  of  them  to  one  end  of  a  thread  a  yard  long,  the 
other  to  the  other  end.  Extend  a  twine  under  the 
ceiling  of  a  room,  and  put  through  it  at  thirty  inches' 
distance  two  pins  bent  in  the  form  of  fish-hooks- 
On  these  hooks  hang  the  two  bodies,  the  thread  that 
connects  them  extending  parallel  to  the  twine,  which 
thread  being  cut,  they  must  begin  to  fall  at  the  same 
instant.  If  they  take  equal  time  in  falling  to  the 
floor,  it  is  a  proof  that  the  resistance  of  the  air  is  in 
both  cases  equal.  If  the  whole  card  requires  a 
longer  time,  it  shows  that  the  sum  of  the  resistances 


134  Benjamin  Franklin  [i785 

to  the  pieces  of  the  cut  card  is  not  equal  to  the  re- 
sistance of  the  whole  one.1 

This  principle  so  far  confirmed,  I  would  proceed 
to  make  a  larger  experiment,  with  a  shallop,  which 
I  would  rig  in  this  manner.  (Plate  I.,  Fig.  4.)  A  B 
is  a  long  boom,  from  which  are  hoisted  seven  jibs, 
a,  b,  c,  d,  e,  f,  g,  each  a  seventh  part  of  the  whole 
dimensions,  and  as  much  more  as  will  fill  the  whole 
space  when  set  in  an  angle  of  forty-five  degrees,  so 
that  they  may  lap  when  going  before  the  wind,  and 
hold  more  wind  when  going  large.  Thus  rigged, 
when  going  right  before  the  wind,  the  boom  should 
be  brought  at  right  angles  with  the  keel,  by  means 
of  the  sheet  ropes  C  D,  and  all  the  sails  hauled  flat 
to  the  boom. 

These  positions  of  boom  and  sails  to  be  varied  as 
the  wind  quarters.  But  when  the  wind  is  on  the 
beam,  or  when  you  would  turn  to  windward,  the 
boom  is  to  be  hauled  right  fore  and  aft,  and  the  sails 
trimmed  according  as  the  wind  is  more  or  less  against 
your  course. 

It  seems  to  me  that  the  management  of  a  shallop 
so  rigged  would  be  very  easy,  the  sails  being  run  up 
and  down  separately,  so  that  more  or  less  sail  may 
be  made  at  pleasure ;  and  I  imagine  that  there  being 
full  as  much  sail  exposed  to  the  force  of  the  wind 
which  impels  the  vessel  in  its  course,  as  if  the  whole 
were  in  one  piece,  and  the  resistance  of  the  dead  air 
against  the  foreside  of  the  sail  being  diminished,  the 

1  The  motion  of  the  vessel  made  it  inconvenient  to  try  this  simple 
experiment  at  sea,  when  the  proposal  of  it  was  written.  But  it  has 
been  tried  since  we  came  on  shore,  and  succeeded  as  the  other. 


Essays 


i35 


advantage  of  swiftness  would  be  very  considerable; 
besides  that  the  vessel  would  lie  nearer  the  wind. 

Since  we  are  on  the  subject  of  improvements  in 
navigation,  permit  me  to  detain  you  a  little  longer 
with  a  small  relative  observation.  Being,  in  one  of 
my  voyages,  with  ten  merchant  ships  under  convoy 
of  a  frigate  at  anchor  in  Torbay,  waiting  for  a  wind 
to  go  to  the  westward,  it  came  fair,  but  brought  in 
with  it  a  considerable  swell.  A  signal  was  given  for 
weighing,  and  we  put  to  sea  all  together ;  but  three 
of  the  ships  left  their  anchors,  their  cables  parting 
just  as  the  anchors  came  a-peak.  Our  cable  held, 
and  we  got  up  our  anchor ;  but  the  shocks  the  ship 
felt  before  the  anchor  got  loose  from  the  ground, 
made  me  reflect  on  what  might  possibly  have  caused 
the  breaking  of  the  other  cables;  and  I  imagined  it 
might  be  the  short  bending  of  the  cable  just  without 
the  hawse-hole,  from  a  horizontal  to  an  almost  verti- 
cal position,  and  the  sudden  violent  jerk  it  receives 
by  the  rising  of  the  head  of  the  ship  on  the  swell  of  a 
wave  while  in  that  position.  For  example,  sup- 
pose a  vessel  hove  up  so  as  to  have  her  head  nearly 
over  her  anchor,  which  still  keeps  its  hold,  perhaps 
in  a  tough  bottom ;  if  it  were  calm,  the  cable  still  out 
would  form  nearly  a  perpendicular  line,  measuring 
the  distance  between  the  hawse-hole  and  the  anchor ; 
but  if  there  is  a  swell,  her  head  in  the  trough  of  the 
sea  will  fall  below  the  level,  and  when  lifted  on  the 
wave  will  be  much  above  it.  In  the  first  case  the 
cable  will  hang  loose  and  bend  perhaps  as  in  figure  5. 
In  the  second  case,  figure  6,  the  cable  will  be  drawn 
straight  with  a  jerk,  must  sustain  the  whole  force  of 


136 


Benjamin  Franklin 


the  rising  ship,  and  must  either  loosen  the  anchor, 
resist  the  rising  force  of  the  ship,  or  break.  But  why- 
does  it  break  at  the  hawse-hole  ? 

Let  us  suppose  it  a  cable  of  three  inches  diameter, 
and  represented  by  figure  7.  If  this  cable  is  to  be 
bent  round  the  corner  A,  it  is  evident  that  either  the 
part  of  the  triangle  contained  between  the  letters  a, 
b,  c,  must  stretch  considerably,  and  those  most  that 
are  nearest  the  surface ;  or  that  the  parts  between  d, 
e,  f,  must  be  compressed ;  or  both,  which  most  prob- 
ably happens.  In  this  case,  the  lower  half  of  the 
thickness  affords  no  strength  against  the  jerk,  it  not 
being  strained,  the  upper  half  bears  the  whole,  and 
the  yarns  near  the  upper  surface  being  first  and  most 
strained,  break  first,  and  the  next  yarns  follow;  for 
in  this  bent  situation  they  cannot  bear  the  strain  all 
together,  and  each  contribute  its  strength  to  the 
whole,  as  they  do  when  the  cable  is  strained  in  a 
straight  line. 

To  remedy  this,  methinks  it  would  be  well  to  have 
a  kind  of  large  pulley  wheel,  fixed  in  the  hawse-hole, 
suppose  of  two  feet  diameter,  over  which  the  cable 
might  pass;  and,  being  there  bent  gradually  to  the 
round  of  the  wheel,  would  thereby  be  more  equally 
strained,  and  better  able  to  bear  the  jerk,  which  may 
save  the  anchor,  and  by  that  means  in  the  course  of 
the  voyage  may  happen  to  save  the  ship. 

One  maritime  observation  more  shall  finish  this 
letter.  I  have  been  a  reader  of  newspapers  now  near 
seventy  years,  and  I  think  few  years  pass  without  an 
account  of  some  vessel  met  with  at  sea,  with  no  liv- 
ing soul  on  board,  and  so  many  feet  of  water  in  her 


Essays 


i37 


hold,  which  vessel  has  nevertheless  been  saved  and 
brought  into  port;  and  when  not  met  with  at  sea, 
such  forsaken  vessels  have  often  come  ashore  on 
some  coast.  The  crews,  who  have  taken  to  their 
boats  and  thus  abandoned  such  vessels,  are  some- 
times met  with  and  taken  up  at  sea  by  other  ships, 
sometimes  reach  a  coast,  and  are  sometimes  never 
heard  of.  Those  that  give  an  account  of  quitting 
their  vessels  generally  say  that  she  sprung  a  leak, 
that  they  pumped  for  some  time,  that  the  water  con- 
tinued to  rise  upon  them,  and  that,  despairing  to 
save  her,  they  had  quitted  her,  lest  they  should  go 
down  with  her.  It  seems  by  the  event  that  this  fear 
was  not  always  well  founded,  and  I  have  endeavored 
to  guess  at  the  reason  of  the  people's  too  hasty 
discouragement. 

When  a  vessel  springs  a  leak  near  her  bottom,  the 
water  enters  with  all  the  force  given  by  the  weight 
of  the  column  of  water  without,  which  force  is  in  pro- 
portion to  the  difference  of  level  between  the  water 
without  and  that  within.  It  enters  therefore  with 
more  force  at  first  and  in  greater  quantity  than  it 
can  afterwards,  when  the  water  within  is  higher. 
The  bottom  of  the  vessel  too  is  narrower,  so  that  the 
same  quantity  of  water  coming  into  that  narrow  part, 
rises  faster  than  when  the  space  for  it  to  flow  in  is 
larger.  This  helps  to  terrify.  But,  as  the  quantity 
entering  is  less  and  less  as  the  surfaces  without  and 
within  become  more  nearly  equal  in  height,  the 
pumps,  that  could  not  keep  the  water  from  rising  at 
first,  might  afterwards  be  able  to  prevent  its  rising 
higher,  and  the  people  might  have  remained  on  board 


138  Benjamin  Franklin  [1785 

in  safety,  without  hazarding  themselves  in  an  open 
boat  on  the  wide  ocean.  (Fig.8.) 

Besides  the  greater  equality  in  the  height  of  the 
two  surfaces,  there  may  sometimes  be  other  causes 
that  retard  the  farther  sinking  of  a  leaky  vessel.  The 
rising  water  within  may  arrive  at  quantities  of  light 
wooden  work,  empty  chests,  and  particularly  empty 
water-casks,  which  if  fixed  so  as  not  to  float  them- 
selves may  help  to  sustain  her.  Many  bodies  which 
compose  a  ship's  cargo  may  be  specifically  lighter 
than  water ;  all  these  when  out  of  water  are  an  addi- 
tional weight  to  that  of  the  ship,  and  she  is  in  pro- 
portion pressed  deeper  into  the  water;  but,  as  soon 
as  these  bodies  are  immersed,  they  weigh  no  longer 
on  the  ship,  but,  on  the  contrary,  if  fixed,  they  help 
to  support  her,  in  proportion  as  they  are  specifically 
lighter  than  the  water.  And  it  should  be  remem- 
bered that  the  largest  body  of  a  ship  may  be  so  bal- 
anced in  the  water  that  an  ounce  less  or  more  of 
weight  may  leave  her  at  the  surface  or  sink  her  to 
the  bottom.  There  are  also  certain  heavy  cargoes 
that,  when  the  water  gets  at  them,  are  continually 
dissolving,  and  thereby  lightening  the  vessel,  such 
as  salt  and  sugar.  And  as  to  water-casks,  men- 
tioned above,  since  the  quantity  of  them  must  be 
great  in  ships  of  war,  where  the  number  of  men  con- 
sume a  great  deal  of  water  every  day,  if  it  had  been 
made  a  constant  rule  to  bung  them  up  as  fast  as  they 
were  emptied,  and  to  dispose  the  empty  casks  in 
proper  situations,  I  am  persuaded  that  many  ships 
which  have  been  sunk  in  engagements,  or  have  gone 
down  afterwards,  might  with  the  unhappy  people 


785] 


Essays 


139 


have  been  saved ;  as  well  as  many  of  those  which  in 
the  last  war  foundered  and  were  never  heard  of- 
While  on  this  topic  of  sinking,  one  cannot  help  recol- 
lecting the  well-known  practice  of  the  Chinese,  to 
divide  the  hold  of  a  great  ship  into  a  number  of 
separate  chambers  by  partitions  tight  caulked  (of 
which  you  gave  a  model  in  your  boat  upon  the 
Seine),  so  that,  if  a  leak  should  spring  in  one  of  them, 
the  others  are  not  affected  by  it;  and,  though  that 
chamber  should  fill  to  a  level  with  the  sea,  it  would 
not  be  sufficient  to  sink  the  vessel.  We  have  not 
imitated  this  practice.  Some  little  disadvantage  it 
might  occasion  in  the  stowage,  is  perhaps  one  reason, 
though  that  I  think  might  be  more  than  compen- 
sated by  an  abatement  in  the  insurance  that  would 
be  reasonable,  and  by  a  higher  price  taken  of  pas- 
sengers, who  would  rather  prefer  going  in  such  a 
vessel.  But  our  seafaring  people  are  brave,  despise 
danger,  and  reject  such  precautions  of  safety,  being 
cowards  only  in  one  sense,  that  of  fearing  to  be 
thought  afraid. 

I  promised  to  finish  my  letter  with  the  last  observa- 
tion, but  the  garrulity  of  the  old  man  has  got  hold  of 
me,  and,  as  I  may  never  have  another  occasion  of 
writing  on  this  subject,  I  think  I  may  as  well  now, 
once  for  all,  empty  my  nautical  budget,  and  give  you 
all  the  thoughts  that  have  in  my  various  long  voy- 
ages occurred  to  me  relating  to  navigation.  I  am 
sure,  that  in  you  they  will  meet  with  a  candid  judge, 
who  will  excuse  my  mistakes  on  account  of  my  good 
intention. 

There  are  six  accidents,  that  may  occasion  the  loss 


140  Benjamin  Franklin  [i785 

of  ships  at  sea.  We  have  considered  one  of  them, 
that  of  foundering  by  a  leak.  The  other  five  are: 
i.  Oversetting  by  sudden  flaws  of  wind,  or  by  carry- 
ing sail  beyond  the  bearing.  2.  Fire  by  accident  or 
carelessness.  3.  A  heavy  stroke  of  lightning,  mak- 
ing a  breach  in  the  ship,  or  firing  the  powder.  4. 
Meeting  and  shocking  with  other  ships  in  the  night. 
5.  Meeting  in  the  night  with  islands  of  ice. 

To  that  of  oversetting,  privateers  in  their  first 
cruise  have,  as  far  as  has  fallen  within  my  knowledge 
or  information,  been  more  subject  than  any  other 
kind  of  vessels.  The  double  desire  of  being  able  to 
overtake  a  weaker  flying  enemy,  or  escape  when  pur- 
sued by  a  stronger,  has  induced  the  owners  to  over- 
mast  their  cruisers,  and  to  spread  too  much  canvas ; 
and  the  great  number  of  men  not  seamen,  who,  being 
upon  deck  when  a  ship  heels  suddenly,  are  huddled 
down  to  leeward,  and  increase  by  their  weight  the 
effect  of  the  wind.  This  therefore  should  be  more 
attended  to  and  guarded  against,  especially  as  the 
advantage  of  lofty  masts  is  problematical.  For  the 
upper  sails  have  greater  power  to  lay  a  vessel  more 
on  her  side,  which  is  not  the  most  advantageous 
position  for  going  swiftly  through  the  water.  And 
hence  it  is  that  vessels,  which  have  lost  their  lofty 
masts,  and  been  able  to  make  little  more  sail  after- 
wards than  permitted  the  ship  to  sail  upon  an  even 
keel,  have  made  so  much  way,  even  under  jury  masts, 
as  to  surprise  the  mariners  themselves.  But  there 
is,  besides,  something  in  the  modern  form  of  our 
ships,  that  seems  as  if  calculated  expressly  to  allow 
their  oversetting  more  easily.    The  sides  of  a  ship, 


1785]  Essays  141 

instead  of  spreading  out  as  they  formerly  did  in  the 
upper  works,  are  of  late  years  turned  in  so  as  to 
make  the  body  nearly  round,  and  more  resembling  a 
cask.  I  do  not  know  what  the  advantages  of  this 
construction  are,  except  that  such  ships  are  not 
easily  boarded.  To  me  it  seems  a  contrivance  to 
have  less  room  in  a  ship  at  nearly  the  same  expense. 
For  it  is  evident  that  the  same  timber  and  plank 
consumed  in  raising  the  sides  from  a  to  b,  and  from 
d  to  c,  would  have  raised  them  from  a  to  e,  and  from 
d  to  /,  fig.  9.  In  this  form  all  the  spaces  between 
e,  a,  b,  and  c,  d,  f,  would  have  been  gained,  the  deck 
would  have  been  larger,  the  men  would  have  had 
more  room  to  act,  and  not  have  stood  so  thick  in  the 
way  of  the  enemy's  shot;  and  the  vessel,  the  more 
she  was  laid  down  on  her  side,  the  more  bearing  she 
would  meet  with,  and  more  effectual  to  support  her, 
as  being  farther  from  the  centre.  Whereas,  in  the 
present  form,  her  ballast  makes  the  chief  part  of  her 
bearing,  without  which  she  would  turn  in  the  sea 
almost  as  easily  as  a  barrel.  More  ballast  by  this 
means  becomes  necessary,  and  that,  sinking  a  vessel 
deeper  in  the  water  occasions  more  resistance  to  her 
going  through  it.  The  Bermudian  sloops  still  keep 
with  advantage  to  the  old  spreading  form. 

The  islanders  in  the  great  Pacific  Ocean,  though 
they  have  no  large  ships,  are  the  most  expert  boat- 
sailors  in  the  world,  navigating  that  sea  safely  with 
their  proas,  which  they  prevent  oversetting  by  vari- 
ous means.  Their  sailing  proas  for  this  purpose  have 
outriggers  generally  to  windward  above  the  water, 
on  which  one  or  more  men  are  placed,  to  move 


142  Benjamin  Franklin  [i785 

occasionally  farther  from  or  nearer  to  the  vessel  as 
the  wind  freshens  or  slackens.  But  some  have  their 
outriggers  to  leeward,  which,  resting  on  the  water, 
support  the  boat  so  as  to  keep  her  upright  when 
pressed  down  by  the  wind.  Their  boats,  moved  by 
oars  or  rather  by  paddles,  are,  for  long  voyages, 
fixed  two  together  by  cross  bars  of  wood  that  keep 
them  at  some  distance  from  each  other,  and  so  ren- 
der their  oversetting  next  to  impossible.  How  far 
this  may  be  practicable  in  larger  vessels,  we  have 
not  yet  sufficient  experience.  I  know  of  but  one 
trial  made  in  Europe,  which  was  about  one  hundred 
years  since,  by  Sir  William  Petty.  He  built  a  double 
vessel,  to  serve  as  a  packet-boat  between  England 
and  Ireland.  Her  model  still  exists  in  the  museum 
of  the  Royal  Society,  where  I  have  seen  it.  By  the 
accounts  we  have  of  her,  she  answered  well  the  pur- 
pose of  her  construction,  making  several  voyages; 
and,  though  wrecked  at  last  by  a  storm,  the  misfor- 
tune did  not  appear  owing  to  her  particular  con- 
struction, since  many  other  vessels  of  the  common 
form  were  wrecked  at  the  same  time.  The  advan- 
tage of  such  a  vessel  is,  that  she  needs  no  ballast, 
therefore  swims  either  lighter,  or  will  carry  more 
goods;  and  that  passengers  are  not  so  much  incom- 
moded by  her  rolling;  to  which  may  be  added,  that 
if  she  is  to  defend  herself  by  her  cannon,  they  will 
probably  have  more  effect,  being  kept  more  gener- 
ally in  a  horizontal  position,  than  those  in  common 
vessels.  I  think,  however,  that  it  would  be  an 
improvement  of  that  model,  to  make  the  sides 
which  are  opposed  to  each  other  perfectly  parallel, 


I7«5] 


Essays 


143 


though  the  other  sides  are  formed  as  in  common, 
thus,  figure  10. 

The  building  of  a  double  ship  would  indeed  be 
more  expensive  in  proportion  to  her  burthen;  and 
that,  perhaps,  is  sufficient  to  discourage  the  method. 

The  accident  of  fire  is  generally  well  guarded 
against  by  the  prudent  captain's  strict  orders  against 
smoking  between  decks,  or  carrying  a  candle  there 
out  of  a  lantern.  But  there  is  one  dangerous  prac- 
tice which  frequent  terrible  accidents  have  not  yet 
been  sufficient  to  abolish — that  of  carrying  store 
spirits  to  sea  in  casks.  Two  large  ships,  the  Serapis 
and  the  Duke  of  Athol,  one  an  East  Indiaman,  the 
other  a  frigate,  have  been  burnt  within  these  two  last 
years,  and  many  lives  miserably  destroyed  by  draw- 
ing spirits  out  of  a  cask  near  a  candle.  It  is  high 
time  to  make  it  a  general  rule  that  all  the  ship's 
stores  of  spirits  should  be  carried  in  bottles. 

The  misfortune  by  a  stroke  of  lightning  I  have  in 
my  former  writings  endeavored  to  show  a  method  of 
guarding  against,  by  a  chain  and  pointed  rod,  ex- 
tending, when  run  up,  from  above  the  top  of  the 
mast  to  the  sea.  These  instruments  are  now  made 
and  sold  at  a  reasonable  price  by  Nairne  &  Co.,  in 
London,  and  there  are  several  instances  of  success 
attending  the  use  of  them.  They  are  kept  in  a  box, 
and  may  be  run  up  and  fixed  in  about  five  minutes, 
on  the  apparent  approach  of  a  thundergust. 

Of  the  meeting  and  shocking  with  other  ships 
in  the  night,  I  have  known  two  instances  in  voy- 
ages between  London  and  America.  In  one,  both 
ships  arrived,  though  much  damaged,  each  reporting 


144  Benjamin  Franklin  [i785 

their  belief  that  the  other  must  have  gone  to  the 
bottom.  In  the  other,  only  one  got  to  port ;  the  other 
was  never  afterwards  heard  of.  These  instances 
happened  many  years  ago,  when  the  commerce 
between  Europe  and  America  was  not  a  tenth 
part  of  what  it  is  at  present,  ships  of  course  thinner 
scattered,  and  the  chance  of  meeting  proportionably 
less.  It  has  long  been  the  practice  to  keep  a  look- 
out before  in  the  channel,  but  at  sea  it  has  been 
neglected.  If  it  is  not  at  present  thought  worth 
while  to  take  that  precaution,  it  will  in  time  become 
of  more  consequence,  since  the  number  of  ships  at 
sea  is  continually  augmenting.  A  drum  frequently 
beat  or  a  bell  rung  in  a  dark  night  might  help  to 
prevent  such  accidents. 

Islands  of  ice  are  frequently  seen  off  the  banks  of 
Newfoundland  by  ships  going  between  North  Amer- 
ica and  Europe.  In  the  daytime  they  are  easily 
avoided,  unless  in  a  very  thick  fog.  I  remember 
two  instances  of  ships  running  against  them  in  the 
night.  The  first  lost  her  bowsprit,  but  received  little 
other  damage.  The  other  struck  where  the  warmth 
of  the  sea  had  wasted  the  ice  next  to  it,  and  a  part 
hung  over  above.  This  perhaps  saved  her,  for  she 
was  under  great  way;  but  the  upper  part  of  the 
cliff,  taking  her  foretopmast,  broke  the  shock,  though 
it  carried  away  the  mast.  She  disengaged  herself 
with  some  difficulty ,  and  got  safe  into  port ;  but  the 
accident  shows  the  possibility  of  other  ships  being 
wrecked  and  sunk  by  striking  those  vast  masses  of 
ice,  of  which  I  have  seen  one  that  we  judged  to  be 
seventy  feet  high  above  the  water,  consequently 


1785] 


Essays 


145 


eight  times  as  much  under  water;  and  it  is  another 
reason  for  keeping  a  good  look-out  before,  though  far 
from  any  coast  that  may  threaten  danger. 

It  is  remarkable  that  the  people  we  consider  as 
savages  have  improved  the  art  of  sailing  and  row- 
ing boats  in  several  points  beyond  what  we  can 
pretend  to. 

We  have  no  sailing  boats  equal  to  the  flying  proas 
of  the  South  Seas,  no  rowing  or  paddling  boat  equal 
to  that  of  the  Greenlanders  for  swiftness  and  safety. 
The  birch  canoes  of  the  North  American  Indians 
have  also  some  advantageous  properties.  They  are 
so  light  that  two  men  may  carry  one  of  them  over- 
land which  is  capable  of  carrying  a  dozen  upon  the 
water;  and  in  heeling  they  are  not  so  subject  to  take 
in  water  as  our  boats,  the  sides  of  which  are  lowest 
in  the  middle  where  it  is  most  likely  to  enter,  this 
being  highest  in  that  part,  as  in  figure  1 1 . 

The  Chinese  are  an  enlightened  people,  the  most 
anciently  civilized  of  any  existing,  and  their  arts  are 
ancient,  a  presumption  in  their  favor ;  their  method 
of  rowing  their  boats  differs  from  ours,  the  oars 
being  worked  either  two-a-stern,  as  we  scull,  or  on 
the  sides  with  the  same  kind  of  motion,  being  hung 
parallel  to  the  keel  on  a  rail,  and  always  acting  in  the 
water,  not  perpendicular  to  the  side,  as  ours  are,  nor 
lifted  out  at  every  stroke,  which  is  a  loss  of  time, 
and  the  boat  in  the  interval  loses  motion.  They  see 
our  manner  and  we  theirs,  but  neither  are  disposed 
to  learn  of  or  copy  the  other. 

To  the  several  means  of  moving  boats  mentioned 
above,  may  be  added  the  singular  one  lately  exhib- 


146  Benjamin  Franklin  [1785 

ited  at  Javelle,  on  the  Seine  below  Paris,  where  a 
clumsy  boat  was  moved  across  that  river  in  three 
minutes  by  rowing,  not  in  the  water,  but  in  the  air, 
that  is,  by  whirling  round  a  set  of  windmill  vanes 
fixed  to  a  horizontal  axis,  parallel  to  the  keel,  and 
placed  at  the  head  of  the  boat.  The  axis  was  bent 
into  an  elbow  at  the  end,  by  the  help  of  which  it  was 
turned  by  one  man  at  a  time.  I  saw  the  operation 
at  a  distance.  The  four  vanes  appeared  to  be  about 
five  feet  long,  and  perhaps  two  and  a  half  wide.  The 
weather  was  calm.  The  labor  appeared  to  be  great 
for  one  man,  as  the  two  several  times  relieved  each 
other.  But  the  action  upon  the  air  by  the  oblique 
surfaces  of  the  vanes  must  have  been  considerable, 
as  the  motion  of  the  boat  appeared  tolerably  quick 
going  and  returning;  and  she  returned  to  the  same 
place  from  whence  she  first  set  out,  notwithstanding 
the  current.  This  machine  is  since  applied  to  the 
moving  of  air-balloons;  an  instrument  similar  may 
be  contrived  to  move  a  boat  by  turning  under  water. 

Several  mechanical  projectors  have  at  different 
times  proposed  to  give  motion  to  boats,  and  even  to 
ships,  by  means  of  circular  rowing,  or  paddles  placed 
on  the  circumference  of  wheels  to  be  turned  con- 
stantly on  each  side  of  the  vessel;  but  this  method, 
though  frequently  tried,  has  never  been  found  so 
effectual  as  to  encourage  a  continuance  of  the  prac- 
tice. I  do  not  know  that  the  reason  has  hitherto 
been  given.  Perhaps  it  may  be  this,  that  great  part 
of  the  force  employed  contributes  little  to  the  motion. 
For  instance  (fig.  12),  of  the  four  paddles  a,  b,  c,  d, 
all  under  water,  and  turning  to  move  a  boat  from 


1785] 


Essays 


i47 


X  to  Y,  c  has  the  most  power,  b  nearly  though  not 
quite  as  much,  their  motion  being  nearly  horizontal ; 
but- the  force  employed  in  moving  a  is  consumed  in 
pressing  almost  downright  upon  the  water  till  it 
comes  to  the  place  of  b;  and  the  force  employed  in 
moving  d  is  consumed  in  lifting  the  water  till  d 
arrives  at  the  surface ;  by  which  means  much  of  the 
labor  is  lost.  It  is  true  that,  by  placing  the  wheels 
higher  out  of  the  water,  this  waste  labor  will  be 
diminished  in  a  calm,  but,  where  a  sea  runs,  the 
wheels  must  unavoidably  be  often  dipped  deep  in 
the  waves,  and  the  turning  of  them  thereby  rendered 
very  laborious  to  little  purpose. 

Among  the  various  means  of  giving  motion  to  a 
boat,  that  of  M.  Bernoulli  appears  one  of  the  most 
singular,  which  was  to  have  fixed  in  the  boat  a  tube 
in  the  form  of  an  L,  the  upright  part  to  have  a  fun- 
nel-kind of  opening  at  top,  convenient  for  filling  the 
tube  with  water;  which,  descending  and  passing 
through  the  lower  horizontal  part,  and  issuing  in  the 
middle  of  the  stern,  but  under  the  surface  of  the 
river,  should  push  the  boat  forward.  There  is  no 
doubt  that  the  force  of  the  descending  water  would 
have  a  considerable  effect,  greater  in  proportion  to 
the  height  from  which  it  descended;  but  then  it  is 
to  be  considered,  that  every  bucketful  pumped  or 
dipped  up  into  the  boat,  from  its  side  or  through  its 
bottom,  must  have  its  vis  inertia  overcome  so  as  to 
receive  the  motion  of  the  boat,  before  it  can  come 
to  give  motion  by  its  descent;  and  that  will  be  a 
deduction  from  the  moving  power.  To  remedy  this, 
I  would  propose  the  addition  of  another  such  L 


148  Benjamin  Franklin  [1785 

pipe,  and  that  they  should  stand  back  to  back  in  the 
boat  thus,  figure  13;  the  forward  one  being  worked 
as  a  pump,  and  sucking  in  the  water  at  the  head  of 
the  boat,  would  draw  it  forward  while  pushed  in  the 
same  direction  by  the  force  of  the  stern.  And  after 
all  it  should  be  calculated  whether  the  labor  of 
pumping  would  be  less  than  that  of  rowing.  A  fire- 
engine  might  possibly  in  some  cases  be  applied  in 
this  operation  with  advantage. 

Perhaps  this  labor  of  raising  water  might  be 
spared,  and  the  whole  force  of  a  man  applied  to  the 
moving  of  a  boat  by  the  use  of  air  instead  of  water. 
Suppose  the  boat  constructed  in  this  form,  figure  14. 

A,  a  tube  round  or  square  of  two  feet  diameter,  in 
which  a  piston  may  move  up  and  down.  The  piston 
to  have  valves  in  it,  opening  inwards  to  admit  air 
when  the  piston  rises;  and  shutting,  when  it  is 
forced  down  by  means  of  the  lever  B  turning  on  the 
centre  C.  The  tube  to  have  a  valve  D,  to  open 
when  the  piston  is  forced  down,  and  let  the  air  pass 
out  at  E,  which  striking  forcibly  against  the  water 
abaft  must  push  the  boat  forward.  If  there  is  added 
an  air-vessel  F  properly  valved  and  placed,  the  force 
would  continue  to  act  while  a  fresh  stroke  is  taken 
with  the  lever.  The  boatman  might  stand  with  his 
back  to  the  stern,  and  putting  his  hands  behind  him, 
work  the  motion  by  taking  hold  of  the  cross  bar  at 

B,  while  another  should  steer;  or,  if  he  had  two  such 
pumps,  one  on  each  side  of  the  stern,  with  a  lever 
for  each  hand,  he  might  steer  himself  by  working 
occasionally  more  or  harder  with  either  hand,  as 
watermen  now  do  with  a  pair  of  sculls.    There  is  no 


Essays 


149 


position  in  which  the  body  of  a  man  can  exert  more 
strength  than  in  pulling  right  upwards. 

To  obtain  more  swiftness,  greasing  the  bottom  of 
a  vessel  is  sometimes  used,  and  with  good  effect.  I 
do  not  know  that  any  writer  has  hitherto  attempted 
to  explain  this.  At  first  sight,  one  would  imagine 
that  though  the  friction  of  a  hard  body  sliding  on 
another  hard  body,  and  the  resistance  occasioned  by 
that  friction,  might  be  diminished  by  putting  grease 
between  them,  yet  that  a  body  sliding  on  a  fluid, 
such  as  water,  should  have  no  need  of,  nor  receive, 
any  advantage  from  such  greasing.  But  the  fact  is 
not  disputed.  And  the  reason  perhaps  may  be  this. 
The  particles  of  water  have  a  mutual  attraction, 
called  the  attraction  of  adhesion.  Water  also  ad- 
heres to  wood,  and  to  many  other  substances,  but 
not  to  grease ;  on  the  contrary,  they  have  a  mutual 
repulsion,  so  that  it  is  a  question  whether,  when  oil 
is  poured  on  water,  they  ever  actually  touch  each 
other;  for  a  drop  of  oil  upon  water,  instead  of  stick- 
ing to  the  spot  where  it  falls,  as  it  would  if  it  fell  on 
a  looking-glass,  spreads  instantly  to  an  immense 
distance  in  a  film  extremely  thin,  which  it  could  not 
easily  do  if  it  touched  and  rubbed  or  adhered  even 
in  a  small  degree  to  the  surface  of  the  water.  Now 
the  adhesive  force  of  water  to  itself,  and  to  other 
substances,  may  be  estimated  from  the  weight  of  it 
necessary  to  separate  a  drop,  which  adheres,  while 
growing,  till  it  has  weight  enough  to  force  the  separa- 
tion and  break  the  drop  off.  Let  us  suppose  the 
drop  to  be  the  size  of  a  pea;  then  there  will  be  as 
many  of  these  adhesions  as  there  are  drops  of  that 


150  Benjamin  Franklin  [1786 

size  touching  the  bottom  of  a  vessel,  and  these  must 
be  broken  by  the  moving  power,  every  step  of  her 
motion  that  amounts  to  a  drop's  breadth ;  and  there 
being  no  such  adhesions  to  break  between  the  water 
and  a  greased  bottom,  may  occasion  the  difference. 

So  much  respecting  the  motion  of  vessels.  But 
we  have  sometimes  occasion  to  stop  their  motion, 
and,  if  a  bottom  is  near  enough,  we  can  cast  anchor. 
Where  there  are  no  soundings,  we  have  as  yet  no 
means  to  prevent  driving  in  a  storm  but  by  lying-to, 
which  still  permits  driving  at  the  rate  of  about  two 
miles  an  hour;  so  that  in  a  storm  continuing  fifty 
hours,  which  is  not  an  uncommon  case,  the  ship  may 
drive  one  hundred  miles  out  of  her  course;  and 
should  she  in  that  distance  meet  with  a  lee  shore,  she 
may  be  lost. 

To  prevent  this  driving  to  leeward  in  deep  water, 
a  swimming  anchor  is  wanting,  which  ought  to  have 
these  properties. 

1.  It  should  have  a  surface  so  large  as,  being  at 
the  end  of  a  hawser  in  the  water,  and  placed  perpen- 
dicularly, should  hold  so  much  of  it,  as  to  bring  the 
ship's  head  to  the  wind,  in  which  situation  the  wind 
has  least  power  to  drive  her. 

2.  It  should  be  able,  by  its  resistance,  to  prevent 
the  ship's  receiving  way. 

3.  It  should  be  capable  of  being  situated  below 
the  heave  of  the  sea,  but  not  below  the  undertow. 

4.  It  should  not  take  up  much  room  in  the  ship. 

5.  It  should  be  easily  thrown  out,  and  put  into 
its  proper  situation. 

6.  It  should  be  easy  to  take  in  again,  and  stow  away. 


1785] 


Essays 


151 


An  ingenious  old  mariner,  whom  I  formerly  knew, 
proposed,  as  a  swimming  anchor  for  a  large  ship,  to 

;  have  a  stem  of  wood  twenty-five  feet  long  and  four 
inches  square,  with  four  boards  of  eighteen,  sixteen, 
fourteen,  and  twelve  feet  long,  and  one  foot  wide, 

I  the  boards  to  have  their  substance  thickened  several 
inches  in  the  middle  by  additional  wood,  and  to  have 
each  a  four-inch  square  hole  through  its  middle,  to 

j  permit  its  being  slipped  on  occasionally  upon  the 
stem,  and  at  right  angles  with  it;  where,  all  being 
placed  and  fixed  at  four  feet  distance  from  each 
other,  it  would  have  the  appearance  of  the  old  mathe- 
matical instrument  called  a  forestaff .  This  thrown 
into  the  sea,  and  held  by  a  hawser  veered  out  to 
some  length,  he  conceived  would  bring  a  vessel  up, 
and  prevent  her  driving,  and  when  taken  in  might 
be  stowed  away  by  separating  the  boards  from  the 
stem;  figure  15.  Probably  such  a  swimming  anchor 
would  have  some  good  effect ;  but  it  is  subject  to  this 
objection,  that,  lying  on  the  surface  of  the  sea,  it  is 
liable  to  be  hove  forward  by  every  wave,  and  thereby 
give  so  much  leave  for  the  ship  to  drive. 

Two  machines  for  this  purpose  have  occurred  to 
me,  which,  though  not  so  simple  as  the  above,  I 
imagine  would  be  more  effectual,  and  more  easily 
manageable.  I  will  endeavor  to  describe  them,  that 
they  may  be  submitted  to  your  judgment,  whether 
either  would  be  serviceable;  and,  if  they  would,  to 
which  we  should  give  the  preference. 

The  first  is  to  be  formed  and  to  be  used  in  the 
water  on  almost  the  same  principles  with  those  of  a 
paper  kite  used  in  the  air.    Only,  as  the  paper  kite 


152  Benjamin  Franklin  u785 

rises  in  the  air,  this  is  to  descend  in  the  water.  Its 
dimensions  will  be  different  for  ships  of  different  size. 

To  make  one  of  suppose  fifteen  feet  high:  take  a 
small  spar  of  that  length  for  the  backbone,  A  B, 
figure  1 6,  a  smaller  of  half  that  length,  C  D,  for  the 
cross  piece.  Let  these  be  united  by  a  bolt  at  E,  yet 
so  as  that  by  turning  on  the  bolt  they  may  be  laid 
parallel  to  each  other.  Then  make  a  sail  of  strong 
canvas  in  the  shape  of  figure  17.  To  form  this, 
without  waste  of  sailcloth,  sew  together  pieces  of  the 
proper  length,  and  for  half  the  breadth,  as  in  figure 
18,  then  cut  the  hole  in  the  diagonal  lines,  a,  b,  c, 
and  turn  the  piece  F  so  as  to  place  its  broad  part 
opposite  to  that  of  the  piece  G,  and  the  piece  H,  in 
like  manner  opposite  to  I,  which,  when  all  sewed  to- 
gether, will  appear  as  in  figure  17.  This  sail  is  to  be 
extended  on  the  cross  of  figure  16,  the  top  and  bottom 
points  well  secured  to  the  ends  of  the  long  spar;  the 
two  side  points  d,  e,  fastened  to  the  ends  of  two  cords, 
which,  coming  from  the  angle  of  the  loop  (which 
must  be  similar  to  the  loop  of  a  kite),  pass  through 
two  rings  at  the  ends  of  the  short  spar,  so  as  that  on 
pulling  upon  the  loop  the  sail  will  be  drawn  to  its 
extent.  The  whole  may,  when  aboard,  be  furled  up, 
as  in  figure  19,  having  a  rope  from  its  broad  end,  to 
which  is  tied  a  bag  of  ballast  for  keeping  that  end 
downwards  when  in  the  water,  and  at  the  other  end 
another  rope  with  an  empty  keg  at  its  end  to  float  on 
the  surface;  this  rope  long  enough  to  permit  the 
kite's  descending  into  the  undertow,  or  if  you  please 
lower  into  still  water.  It  should  be  held  by  a  hawser. 
To  get  it  home  easily,  a  small  loose  rope  may  be 


17851 


Essays 


153 


veered  out  with  it,  fixed  to  the  keg.  Hauling  on 
ithat  rope  will  bring  the  kite  home  with  small  force, 
ithe  resistance  being  small,  as  it  will  then  come 
endways. 

It  seems  probable  that  such  a  kite  at  the  end  of  a 
long  hawser  would  keep  a  ship  with  her  head  to  the 
wind,  and,  resisting  every  tug,  would  prevent  her 
driving  so  fast  as  when  her  side  is  exposed  to  it  and 
nothing  to  hold  her  back.  If  only  half  the  driving 
is  prevented,  so  that  she  moves  but  fifty  miles  in- 
stead of  the  hundred  during  a  storm,  it  may  be  some 
advantage,  both  in  holding  so  much  distance  as  is 
saved,  and  in  keeping  from  a  lee  shore.  If  single 
canvas  should  not  be  found  strong  enough  to  bear 
the  tug  without  splitting,  it  may  be  doubled,  or 
strengthened  by  a  netting  behind  it,  represented  by 
figure  20. 

The  other  machine  for  the  same  purpose  is  to  be 
made  more  in  the  form  of  an  umbrella,  as  repre- 
sented in  figure  21.  The  stem  of  the  umbrella,  a 
square  spar  of  proper  length,  with  four  movable 
arms,  of  which  two  are  represented,  C,  C,  figure  22. 
These  arms  to  be  fixed  in  four  joint  cleats,  as  D,D, 
etc.,  one  on  each  side  of  the  spar,  but  so  as  that  the 
four  arms  may  open  by  turning  on  a  pin  in  the  joint. 
When  open,  they  form  a  cross,  on  which  a  four- 
square canvas  sail  is  to  be  extended,  its  corner  fas- 
tened to  the  ends  of  the  four  arms.  Those  ends  are 
also  to  be  stayed  by  ropes  fastened  to  the  stem  or 
spar,  so  as  to  keep  them  short  of  being  at  right  angles 
with  it;  and  to  the  end  of  one  of  the  arms  should 
be  hung  the  small  bag  of  ballast,  and  to  the  end  of 


154 


Benjamin  Franklin 


the  opposite  arm  the  empty  keg.  This,  on  being 
thrown  into  the  sea,  would  immediately  open;  and 
when  it  had  performed  its  function,  and  the  storm 
over,  a  small  rope  from  its  other  end  being  pulled 
on,  would  turn  it,  close  it,  and  draw  it  easily  home 
to  the  ship.  This  machine  seems  more  simple  in  its 
operation,  and  more  easily  manageable  than  the  first, 
and  perhaps  may  be  as  effectual.1 

Vessels  are  sometimes  retarded,  and  sometimes 
forwarded  in  their  voyages,  by  currents  at  sea,  which 
are  often  not  perceived.  About  the  year  1769  or 
1770  there  was  an  application  made  by  the  Board  of 
Customs  at  Boston  to  the  Lords  of  the  Treasury  in 
London,  complaining  that  the  packets  between  Fal- 
mouth and  New  York  were  generally  a  fortnight 
longer  in  their  passages  than  merchant-ships  from 
London  to  Rhode  Island,  and  proposing  that  for  the 
future  they  should  be  ordered  to  Rhode  Island  in- 
stead of  New  York.  Being  then  concerned  in  the  man- 
agement of  the  American  post-office,  I  happened 
to  be  consulted  on  the  occasion;  and  it  appearing 
strange  to  me  that  there  should  be  such  a  differ- 
ence between  two  places  scarce  a  day's  run  asunder, 
especially  when  the  merchant-ships  are  generally 
deeper  laden  and  more  weakly  manned  than  the 
packets,  and  had  from  London  the  whole  length  of 
the  river  and  channel  to  run  before  they  left  the 
land  of  England,  while  the  packets  had  only  to  go 

1  Captain  Truxtun,  on  board  whose  ship  this  was  written,  has  exe- 
cuted this  proposed  machine;  he  has  given  six  arms  to  the  umbrella; 
they  are  joined  to  the  stem  by  iron  hinges,  and  the  canvas  is  double. 
He  has  taken  it  with  him  to  China.    February,  1786. 


1785] 


Essays 


i55 


from  Falmouth,  I  could  not  but  think  the  fact  mis- 
understood or  misrepresented.  There  happened  then 
to  be  in  London  a  Nantucket  sea-captain  of  my 
acquaintance,  to  whom  I  communicated  the  affair. 
He  told  me  he  believed  the  fact  might  be  true ;  but 
the  difference  was  owing  to  this,  that  the  Rhode 
Island  captains  were  acquainted  with  the  Gulf 
Stream,  which  those  of  the  English  packets  were  not. 
"We  are  well  acquainted  with  that  stream,"  says  he, 
"because  in  our  pursuit  of  whales,  which  keep  near 
the  sides  of  it,  but  are  not  to  be  met  with  in  it,  we 
run  down  along  the  sides,  and  frequently  cross  it  to 
change  our  side;  and  in  crossing  it  have  sometimes 
met  and  spoke  with  those  packets  who  were  in  the 
middle  of  it  and  stemming  it.  We  have  informed 
them  that  they  were  stemming  a  current  that  was 
against  them  to  the  value  of  three  miles  an  hour, 
and  advised  them  to  cross  it  and  get  out  of  it;  but 
they  were  too  wise  to  be  counselled  by  simple  Ameri- 
can fishermen.  When  the  winds  are  but  light,"  he 
added,  "they  are  carried  back  by  the  current  more 
than  they  are  forwarded  by  the  wind;  and,  if  the 
wind  be  good,  the  subtraction  of  seventy  miles  a 
day  from  their  course  is  of  some  importance."  I 
then  observed  it  was  a  pity  no  notice  was  taken  of 
this  current  upon  the  charts,  and  requested  him  to 
mark  it  out  for  me,  which  he  readily  complied  with, 
adding  directions  for  avoiding  it  in  sailing  from 
Europe  to  North  America.  I  procured  it  to  be 
engraved  by  order  from  the  general  post-office,  on 
the  old  chart  of  the  Atlantic,  at  Mount  &  Page's, 
Tower  Hill ;  and  copies  were  sent  down  to  Falmouth 


156 


Benjamin  Franklin 


[1785 


for  the  captains  of  the  packets,  who  slighted  it,  how- 
ever ;  but  it  is  since  printed  in  France,  of  which  edi- 
tion I  hereto  annex  a  copy.1 

This  stream  is  probably  generated  by  the  great 
accumulation  of  water  on  the  eastern  coast  of  Amer- 
ica between  the  tropics,  by  the  trade-winds  which 
constantly  blow  there.  It  is  known  that  a  large 
piece  of  water,  ten  miles  broad  and  generally  only 
three  feet  deep,  has  by  a  strong  wind  had  its  waters 
driven  to  one  side  and  sustained  so  as  to  become  six 
feet  deep,  while  the  windward  side  was  laid  dry. 
This  may  give  some  idea  of  the  quantity  heaped 
upon  the  American  coast,  and  the  reason  of  its  run- 
ning down  in  a  strong  current  through  the  islands 
into  the  Bay  of  Mexico,  and  from  thence  issuing 
through  the  Gulf  of  Florida,  and  proceeding  along 
the  coast  to  the  Banks  of  Newfoundland,  where  it 
turns  off  towards  and  runs  down  through  the  west- 
ern islands.  Having  since  crossed  the  stream  several 
times  in  passing  between  America  and  Europe,  I  have 
been  attentive  to  sundry  circumstances  relating  to 
it,  by  which  to  know  when  one  is  in  it ;  and  besides 
the  gulfweed  with  which  it  is  interspersed,  I  find  that 
it  is  always  warmer  than  the  sea  on  each  side  of  it, 
and  that  it  does  not  sparkle  in  the  night.  I  annex 
hereto  the  observations  made  with  the  thermometer 
in  two  voyages,  and  possibly  may  add  a  third.  It 
will  appear  from  them  that  the  thermometer  may  be 
a  useful  instrument  to  a  navigator,  since  currents 
coming  from  the  northward  into  southern  seas  will 
probably  be  found  colder  than  the  water  of  those 

1  See  Plate,  Vol.  X.,  p.  365,  Franklin's  Works,  Federal  Edition. 


1785] 


Essays 


i57 


seas,  as  the  currents  from  southern  seas  into  north- 
ern are  found  warmer.  And  it  is  not  to  be  won- 
dered that  so  vast  a  body  of  deep  warm  water, 
several  leagues  wide,  coming  from  between  the 
tropics  and  issuing  out  of  the  gulf  into  the  northern 
seas,  should  retain  its  warmth  longer  than  the 
twenty  or  thirty  days  required  to  its  passing  the 
Banks  of  Newfoundland.  The  quantity  is  too  great, 
and  it  is  too  deep  to  be  suddenly  cooled  by  passing 
under  a  cooler  air.  The  air  immediately  over  it, 
however,  may  receive  so  much  warmth  from  it  as  to 
be  rarefied  and  rise,  being  rendered  lighter  than  the 
air  on  each  side  of  the  stream;  hence  those  airs 
must  flow  in  to  supply  the  place  of  the  rising  warm 
air,  and,  meeting  with  each  other,  form  those  tor- 
nados and  waterspouts  frequently  met  with  and 
seen  near  and  over  the  stream.  And  as  the  vapor 
from  a  cup  of  tea  in  a  warm  room,  and  the  breath  of 
an  animal  in  the  same  room,  are  hardly  visible,  but 
become  sensible  immediately  when  out  in  the  cold 
air,  so  the  vapor  from  the  Gulf  Stream  in  warm  lati- 
tudes is  scarcely  visible,  but  when  it  comes  into  the 
cool  air  from  Newfoundland,  it  is  condensed  into  the 
fogs,  for  which  those  parts  are  so  remarkable. 

The  power  of  wind  to  raise  water  above  its  com- 
mon level  in  the  sea  is  known  to  us  in  America  by 
the  high  tides  occasioned  in  all  our  seaports  when  a 
strong  northeaster  blows  against  the  Gulf  Stream. 

The  conclusion  from  these  remarks  is,  that  a  ves- 
sel from  Europe  to  North  America  may  shorten  her 
passage  by  avoiding  to  stem  the  stream,  in  which  the 
thermometer  will  be  very  useful ;  and  a  vessel  from 


158 


Benjamin  Franklin 


[1785 


America  to  Europe  may  do  the  same  by  the  same 
means  of  keeping  in  it.  It  may  have  often  happened 
accidentally  that  voyages  have  been  shortened  by 
these  circumstances.  It  is  well  to  have  the  com- 
mand of  them. 

But  may  there  not  be  another  cause,  independent 
of  winds  and  currents,  why  passages  are  generally 
shorter  from  America  to  Europe  than  from  Europe 
to  America?  This  question  I  formerly  considered 
in  the  following  short  paper: 

On  Board  the  Pennsylvania  Packet,  Captain 
Osborne,  at  Sea,  5  April,  1775. 

14  Suppose  a  ship  to  make  a  voyage  eastward  from 
a  place  in  latitude  400  north,  to  a  place  in  latitude 
500  north,  distance  in  longitude  75  degrees. 

"In  sailing  from  40  to  50,  she  goes  from  a  place 
where  a  degree  of  longitude  is  about  eight  miles 
greater  than  in  the  place  she  is  going  to.  A  de- 
gree is  equal  to  four  minutes  of  time ;  consequently 
the  ship  in  the  harbor  she  leaves,  partaking  of  the 
diurnal  motion  of  the  earth,  moves  two  miles  in  a 
minute  faster  than  when  in  the  port  she  is  going  to 
— which  is  one  hundred  and  twenty  miles  in  an  hour. 

"This  motion  in  a  ship  and  cargo  is  of  great  force; 
and  if  she  could  be  lifted  up  suddenly  from  the  har- 
bor in  which  she  lay  quiet,  and  set  down  instantly 
in  the  latitude  of  the  port  she  was  bound  to,  though 
in  a  calm,  that  force  contained  in  her  would  make 
her  run  a  great  way  at  a  prodigious  rate.  This  force 
must  be  lost  gradually  in  her  voyage,  by  gradual 
impulse  against  the  water,  and  probably  thence 


785] 


Essays 


159 


shorten  the  voyage.  Query.  In  returning,  does  the 
contrary  happen,  and  is  her  voyage  thereby  retarded 
and  lengthened?  "  1 

Would  it  not  be  a  more  secure  method  of  planking 
ships,  if,  instead  of  thick  single  planks  laid  horizon- 
tally, we  were  to  use  planks  of  half  the  thickness, 
and  lay  them  double  and  across  each  other,  as  in 
figure  23?  To  me  it  seems  that  the  difference  of 
expense  would  not  be  considerable,  and  that  the 
ship  would  be  both  tighter  and  stronger. 

The  securing  of  the  ship  is  not  the  only  necessary 
thing;  securing  the  health  of  the  sailors,  a  brave 
and  valuable  order  of  men,  is  likewise  of  great  im- 
portance. With  this  view  the  methods  so  success- 
fully practised  by  Captain  Cook,  in  his  long  voyages, 
cannot  be  too  closely  studied  or  carefully  imitated. 
A  full  account  of  those  methods  is  found  in  Sir  John 
Pringle's  speech,  when  the  medal  of  the  Royal  So- 
ciety was  given  to  that  illustrious  navigator.  I  am 
glad  to  see  in  his  last  voyage,  that  he  found  the 
means  effectual  which  I  had  proposed  for  preserving 
flour,  bread,  etc.,  from  moisture  and  damage.  They 
were  found  dry  and  good  after  being  at  sea  four  years. 
The  method  is  described  in  my  printed  works,  page 
452,  fifth  edition.2  In  the  same,  pages  469,  470, 3  is 
proposed  a  means  of  allaying  thirst  in  case  of  want 
of  fresh  water.    This  has  since  been  practised  in  two 

-  1  Since  this  paper  was  read  at  the  Society,  an  ingenious  member,  Mr. 
Patterson,  has  convinced  the  writer  that  the  returning  voyage  would 
not,  from  this  cause,  be  retarded. — F. 

2  See  Vol.  III.,  p.  433,  Franklin's  Works,  Federal  Edition. 

3  See  letter  to  Miss  Mary  Stevenson,  Aug.  io,  1761,  in  Supplement, 
Vol.  XII.,  Franklin's  Works,  Federal  Edition. 


160  Benjamin  Franklin  [i785 

instances  with  success.  Happy  if  their  hunger,  when 
the  other  provisions  are  consumed,  could  be  relieved 
as  commodiously;  and  perhaps  in  time  this  may  be 
found  not  impossible.  An  addition  might  be  made 
to  their  present  vegetable  provision  by  drying  vari- 
ous roots  in  slices  by  the  means  of  an  oven.  The 
sweet  potato  of  America  and  Spain  is  excellent  for 
this  purpose.  Other  potatoes,  with  carrots,  par- 
snips, and  turnips,  might  be  prepared  and  preserved 
in  the  same  manner. 

With  regard  to  make-shifts  in  cases  of  necessity, 
seamen  are  generally  very  ingenious  themselves. 
They  will  excuse,  however,  the  mention  of  two  or 
three.  If  they  happen  in  any  circumstance,  such  as 
after  shipwreck,  taking  to  their  boat,  or  the  like,  to 
want  a  compass,  a  fine  sewing  needle  laid  on  clear 
water  in  a  cup  will  generally  point  to  the  north, 
most  of  them  being  a  little  magnetical,  or  may  be 
made  so  by  being  strongly  rubbed  or  hammered, 
lying  in  a  north  and  south  direction.  If  their  needle 
is  too  heavy  to  float  by  itself,  it  may  be  supported 
by  little  pieces  of  cork  or  wood.  A  man  who  can 
swim  may  be  aided  in  a  long  traverse  by  his  hand- 
kerchief formed  into  a  kite,  by  two  cross  sticks  ex- 
tending to  the  four  corners;  which,  being  raised  in 
the  air  when  the  wind  is  fair  and  fresh,  will  tow 
him  along  while  lying  on  his  back.  When  force  is 
wanted  to  move  a  heavy  body,  and  there  are  but 
few  hands  and  no  machines,  a  long  and  strong  rope 
may  make  a  powerful  instrument.  Suppose  a  boat 
is  to  be  drawn  up  on  a  beach,  that  she  may  be  out 
of  the  surf;  a  stake  drove  into  the  beach  where  you 


1785]  Essays  161 

would  have  the  boat  drawn,  and  another  to  fasten 
the  end  of  the  rope  to,  which  comes  from  the  boat, 
and  then  applying  what  force  you  have  to  pull  upon 
the  middle  of  the  rope  at  right  angles  with  it,  the 
power  will  be  augmented  in  proportion  to  the  length 
of  rope  between  the  posts.  The  rope  being  fastened 
to  the  stake,  A  and  drawn  upon  in  the  direction 
C  D,  will  slide  over  the  stake  B;  and  when  the  rope 
is  bent  to  the  angle  A  D  B,  represented  by  the 
pricked  line  in  figure  24,  the  boat  will  be  at  B. 

Some  sailors  may  think  the  writer  has  given  him- 
self unnecessary  trouble  in  pretending  to  advise 
them;  for  they  have  a  little  repugnance  to  the 
advice  of  landmen,  whom  they  esteem  ignorant  and 
incapable  of  giving  any  worth  notice;  though  it  is 
certain  that  most  of  their  instruments  were  the  in- 
vention of  landsmen.  At  least  the  first  vessel  ever 
made  to  go  on  the  water  was  certainly  such.  I  will 
therefore  add  only  a  few  words  more,  and  they  shall 
be  addressed  to  passengers. 

When  you  intend  a  long  voyage,  you  may  do  well 
to  keep  your  intention  as  much  as  possible  a  secret, 
or  at  least  the  time  of  your  departure;  otherwise 
you  will  be  continually  interrupted  in  your  prepara- 
tions by  the  visits  of  friends  and  acquaintances,  who 
will  not  only  rob  you  of  the  time  you  want,  but  put 
things  out  of  your  mind,  so  that  when  you  come  to 
sea,  you  have  the  mortification  to  recollect  points 
of  business  that  ought  to  have  been  done,  ac- 
counts you  intended  to  settle,  and  conveniences 
you  had  proposed  to  bring  with  you,  etc.,  etc.,  all 
which  have  been  omitted  through  the  effect  of  these 


162 


Benjamin  Franklin 


[1785 


officious  friendly  visits.  Would  it  not  be  well  if  this 
custom  could  be  changed;  if  the  voyager,  after 
having,  without  interruption,  made  all  his  prepara- 
tions, should  use  some  of  the  time  he  has  left,  in 
going  himself  to  take  leave  of  his  friends  at  their 
own  houses,  and  let  them  come  to  congratulate  him 
on  his  happy  return? 

It  is  not  always  in  your  power  to  make  a  choice  in 
your  captain,  though  much  of  your  comfort  in  the 
passage  may  depend  on  his  personal  character,  as 
you  must  for  so  long  a  time  be  confined  to  his  com- 
pany, and  under  his  direction;  if  he  be  a  sensible, 
sociable,  good-natured,  obliging  man,  you  will  be  so 
much  the  happier.  Such  there  are ;  but,  if  he  hap- 
pens to  be  otherwise,  and  is  only  skilful,  careful, 
watchful,  and  active  in  the  conduct  of  his  ship,  excuse 
the  rest,  for  these  are  the  essentials. 

Whatever  right  you  may  have  by  agreement  in 
the  mass  of  stores  laid  in  by  him  for  the  passengers, 
it  is  good  to  have  some  particular  things  in  your 
own  possession,  so  as  to  be  always  at  your  own 
command. 

1.  Good  water,  that  of  the  ship  being  often  bad. 
You  can  be  sure  of  having  it  good  only  by  bottling  it 
from  a  clear  spring  or  well,  and  in  clean  bottles.  2. 
Good  tea.  3.  Coffee,  ground.  4.  Chocolate.  5.  Wine 
of  the  sort  you  particularly  like,  and  cider.  6. 
Raisins.  7.  Almonds.  8.  Sugar.  9.  Capillaire. 
10.  Lemons.  11.  Jamaica  spirits.  12.  Eggs,  greased. 
13.  Diet  bread.  14.  Portable  soup.  15.  Rusks.  As 
to  fowls,  it  is  not  worth  while  to  have  any  called 
yours,  unless  you  could  have  the  feeding  and  manag- 


1785] 


Essays 


163 


ing  of  them  according  to  your  own  judgment,  under 
your  own  eye.  As  they  are  generally  treated  at 
present  in  ships,  they  are  for  the  most  part  sick,  and 
their  flesh  tough  and  hard  as  whit -leather.  All  sea- 
men have  an  opinion,  broached,  I  suppose,  at  first 
prudently,  for  saving  of  water  when  short,  that  fowls 
do  not  know  when  they  have  drunk  enough,  and 
will  kill  themselves  if  you  give  them  too  much,  so 
they  are  served  with  a  little  only  once  in  two  days. 
This  is  poured  into  troughs  that  lie  sloping,  and 
therefore  immediately  runs  down  to  the  lower  end. 
There  the  fowls  ride  upon  one  another's  backs  to  get 
at  it,  and  some  are  not  happy  enough  to  reach  and 
once  dip  their  bills  in  it.  Thus  tantalized,  and  tor- 
mented with  thirst,  they  cannot  digest  their  dry 
food;  they  fret,  pine,  sicken,  and  die.  Some  are 
found  dead,  and  thrown  overboard  every  morning, 
and  those  killed  for  the  table  are  not  eatable.  Their 
troughs  should  be  in  little  divisions,  like  cups,  to 
hold  the  water  separately,  figure  25.  But  this  is 
never  done.  The  sheep  and  hogs  are  therefore 
your  best  dependence  for  fresh  meat  at  sea,  the 
mutton  being  generally  tolerable  and  the  pork 
excellent. 

It  is  possible  your  captain  may  have  provided  so 
well  in  the  general  stores  as  to  render  some  of  the 
particulars  above  recommended  of  little  or  no  use  to 
you.  But  there  are  frequently  in  the  ship  poorer 
passengers,  who  are  taken  at  a  lower  price,  lodge  in 
the  steerage,  and  have  no  claim  to  any  of  the  cabin 
provisions,  or  to  any  but  those  kinds  that  are  allowed 
the  sailors.    These  people  are  sometimes  dejected, 


164  Benjamin  Franklin  [1785 

sometimes  sick;  there  may  be  women  and  children 
among  them.  In  a  situation  where  there  is  no  going 
to  market  to  purchase  such  necessaries,  a  few  of 
these  your  superfluities,  distributed  occasionally, 
may  be  of  great  service,  restore  health,  save  life, 
make  the  miserable  happy,  and  thereby  afford  you 
infinite  pleasure. 

The  worst  thing  in  ordinary  merchant  ships  is  the 
cookery.  They  have  no  professed  cook,  and  the 
worst  hand  as  a  seaman  is  appointed  to  that  office, 
in  which  he  is  not  only  very  ignorant  but  very  dirty. 
The  sailors  have  therefore  a  saying,  that  God  sends 
meat,  and  the  Devil  cooks.  Passengers  more  piously 
disposed,  and  willing  to  believe  Heaven  orders  all 
things  for  the  best,  may  suppose  that,  knowing  the 
sea  air  and  constant  exercise  by  the  motion  of  the 
vessel  would  give  us  extraordinary  appetites,  bad 
cooks  were  kindly  sent  to  prevent  our  eating  too 
much ;  or  that,  foreseeing  we  should  have  bad  cooks, 
good  appetites  were  furnished  to  prevent  our  starv- 
ing. If  you  cannot  trust  to  these  circumstances,  a 
spirit-lamp,  with  a  blaze-pan,  may  enable  you  to 
cook  some  little  things  for  yourself,  such  as  a  hash,  a 
soup,  etc.  And  it  might  be  well  also  to  have  among 
your  stores  some  potted  meats,  which,  if  well  put 
up,  will  keep  long  good.  A  small  tin  oven,  to  place 
with  the  open  side  before  the  fire,  may  be  another 
good  utensil,  in  which  your  own  servant  may  roast 
for  you  a  bit  of  pork  or  mutton.  You  will  some- 
times be  induced  to  eat  of  the  ship's  salt  beef,  as  it 
is  often  good.  You  will  find  cider  the  best  quencher 
of  that  thirst  which  salt  meat  or  fish  occasions.  The 


1785] 


Essays 


165 


ship  biscuit  is  too  hard  for  some  sets  of  teeth.  It 
may  be  softened  by  toasting.  But  rusk  is  better; 
for  being  made  of  good  fermented  bread,  sliced  and 
baked  a  second  time,  the  pieces  imbibe  the  water 
easily,  soften  immediately,  digest  more  kindly,  and 
are  therefore  more  wholesome  than  the  unfermented 
biscuit.  By  the  way,  rusk  is  the  true  original  biscuit, 
so  prepared  to  keep  for  sea,  biscuit  in  French  signi- 
fying twice  baked.  If  your  dry  peas  boil  hard,  a 
two-pound  iron  shot  put  with  them  into  the  pot 
will,  by  the  motion  of  the  ship,  grind  them  as  fine  as 
mustard. 

The  accidents  I  have  seen  at  sea  with  large  dishes 
of  soup  upon  a  table,  from  the  motion  of  the  ship, 
have  made  me  wish  that  our  potters  or  pewterers 
would  make  soup  dishes  in  divisions,  like  a  set  of 
small  bowls  united  together,  each  containing  about 
sufficient  for  one  person,  in  some  such  form  as  figure 
26;  for  then,  when  the  ship  should  make  a  sudden 
heel,  the  soup  would  not  in  a  body  flow  over  one 
side,  and  fall  into  people's  laps  and  scald  them,  as  is 
sometimes  the  case,  but  would  be  retained  in  the 
separate  divisions,  as  in  figure  27. 

After  these  trifles,  permit  the  addition  of  a  few 
general  reflections.  Navigation,  when  employed  in 
supplying  necessary  provisions  to  a  country  in  want, 
and  thereby  preventing  famines,  which  were  so  fre- 
quent and  destructive  before  the  invention  of  the 
art,  is  undoubtedly  a  blessing  to  mankind.  When 
employed  merely  in  transporting  superfluities,  it  is  a 
question  whether  the  advantage  of  the  employment 
it  affords  is  equal  to  the  mischief  of  hazarding  so 


166  Benjamin  Franklin  [i785 

many  lives  on  the  ocean.  But  when  employed  in 
pillaging  merchants  and  transporting  slaves,  it  is 
clearly  the  means  of  augmenting  the  mass  of  human 
misery.  It  is  amazing  to  think  of  the  ships  and 
lives  risked  in  fetching  tea  from  China,  coffee  from 
Arabia,  sugar  and  tobacco  from  America,  all  which 
our  ancestors  did  well  without.  Sugar  employs  near 
one  thousand  ships,  tobacco  almost  as  many.  For 
the  utility  of  tobacco  there  is  little  to  be  said;  and 
for  that  of  sugar,  how  much  more  commendable 
would  it  be,  if  we  could  give  up  the  few  minutes' 
gratification  afforded  once  or  twice  a  day  by  the 
taste  of  sugar  in  our  tea,  rather  than  encourage  the 
cruelties  exercised  in  producing  it.  An  eminent 
French  moralist  says  that  when  he  considers  the  wars 
we  excite  in  Africa  to  obtain  slaves,  the  numbers 
necessarily  slain  in  those  wars,  the  prisoners  who  per- 
ish at  sea  by  sickness,  bad  provisions,  foul  air,  etc., 
in  the  transportation,  and  how  many  afterwards  die 
from  the  hardships  of  slavery,  he  cannot  look  on  a 
piece  of  sugar  without  conceiving  it  stained  with 
spots  of  human  blood !  Had  he  added  the  considera- 
tion of  the  wars  we  make  to  take  and  retake  the 
sugar  islands  from  one  another,  and  the  fleets  and 
armies  that  perish  in  those  expeditions,  he  might 
have  seen  his  sugar  not  merely  spotted,  but  thor- 
oughly dyed  scarlet  in  grain.  It  is  these  wars  that 
make  the  maritime  powers  of  Europe,  the  inhabit- 
ants of  London  and  Paris,  pay  dearer  for  sugar  than 
those  of  Vienna,  a  thousand  miles  from  the  sea;  be- 
cause their  sugar  costs  not  only  the  price  they  pay 
for  it  by  the  pound,  but  all  they  pay  in  taxes  to 


1785] 


Essays 


167 


maintain  the  fleets  and  armies  that  fight  for  it.1 
With  great  esteem,  I  am,  sir,  your  humble  servant, 

B.  Franklin. 


Appendix  to  the  above  Letter 

REMARKS  UPON  THE  NAVIGATION  FROM  NEWFOUND- 
LAND TO  NEW  YORK  2 

After  you  have  passed  the  Banks  of  Newfoundland 
in  about  the  forty-fourth  degree  of  latitude,  you  will 
meet  with  nothing  till  you  draw  near  the  Isle  of 
Sables,  which  we  commonly  pass  in  latitude  430. 
Southward  of  this  isle,  the  current  is  found  to  ex- 
tend itself  as  far  north  as  410  20'  or  30',  then  it 
turns  towards  the  E.  S.  E.  or  S.  E.  1 J  E. 

Having  passed  the  Isle  of  Sables,  shape  your 
course  for  St.  George's  Banks,  so  as  to  pass  them  in 
about  latitude  400,  because  the  current  southward  of 
those  banks  reaches  as  far  north  as  390.  The  shoals 
of  those  banks  lie  in  400  35/ 

After  having  passed  St.  George's  Banks,  you  must, 
to  clear  Nantucket,  form  your  course  so  as  to  pass 
between  the  latitudes  380  30'  and  400  45'. 

The  most  southern  part  of  the  shoals  of  Nantucket 
lie  in  about  400  45'.  The  northern  part  of  the  cur- 
rent directly  to  the  south  of  Nantucket  is  felt  in 
about  latitude  3 8°  30'. 

1  Several  of  the  closing  paragraphs  of  this  letter  are  the  same  in  sub- 
stance as  the  piece  entitled,  Precautions  to  be  Used  by  Those  Who  are 
about  to  Undertake  a  Sea  Voyage,  Vol.  V.,  p.  307,  Franklin's  Works. 

2  Read  at  a  meeting  of  the  American  Philosophical  Society,  Dec.  2, 
1785. 


1 68  Benjamin  Franklin  [i785 

By  observing  these  directions,  and  keeping  be- 
tween the  stream  and  the  shoals,  the  passage  from 
the  Banks  of  Newfoundland  to  New  York,  Delaware, 
or  Virginia,  may  be  considerably  shortened;  for  so 
you  will  have  the  advantage  of  the  eddy  current, 
which  moves  contrary  to  the  Gulf  Stream.  Whereas, 
if  to  avoid  the  shoals  you  keep  too  far  to  the  south- 
ward, and  get  into  that  stream,  you  will  be  retarded 
by  it  at  the  rate  of  sixty  or  seventy  miles  a  day. 

The  Nantucket  whalemen  being  extremely  well  ac- 
quainted with  the  Gulf  Stream,  its  course,  strength, 
and  extent,  by  their  constant  practice  of  whaling  on 
the  edges  of  it,  from  their  island  quite  down  to  the 
Bahamas,  this  draft  of  that  stream  was  obtained 
from  one  of  them,  Captain  Folger,  and  caused  to 
be  engraved  on  the  old  chart  in  London,  for  the 
benefit  of  navigators,  by 

B.  Franklin. 

Note. — The  Nantucket  captains,  who  are  ac- 
quainted with  this  stream,  make  their  voyages  from 
England  to  Boston  in  as  short  a  time  generally  as 
others  take  in  going  from  Boston  to  England,  viz., 
from  twenty  to  thirty  days. 

A  stranger  may  know  when  he  is  in  the  Gulf 
Stream,  by  the  warmth  of  the  water,  which  is  much 
greater  than  that  of  the  water  on  each  side  of  it.  If 
then  he  is  bound  to  the  westward,  he  should  cross  the 
stream  to  get  out  of  it  as  soon  as  possible. 

B.  Franklin. 


1785] 


Essays 


169 


||  §135. 


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170 


Benjamin  Franklin 


[1785 


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s,i  M.ri  1  1  * 
is  I 


Essays 


171 


Remarks. 

Some  gulf  weed- 
Soundings   off  Belle- 
isle. 

Longitude 
W. 

**>.     On     n  0  r-«           m     0     10  to  «  0     Namo  tno 

<M       m       'tH  ifl               vo       10      M            to       H  M  CO  w  w  O 
0 

O      vo       ton  a              10      •<*■      <t  o>  tJ-  0      00  WOO  f)N 

*t                            tO         PO         (0<M<N<M  MHHl 

Latitude 
N. 

Oi      OV      OtOtO                CO      Pi       10*0 «  Oi      «  Ovvo  \o  CO 

tO         W          CO  M  (MM^-WNMTj-H 

O  . 

O       w       hhn               co      co      ^  miom  101/110101010 
"t               -fr  -"t  -<t               t(-               t1-  ^  rr  tJ-      tt  *  tJ-  tJ- 

Dis- 
tance. 

M          O    OH                      VO         00         *    Ota    IO  Tf-CO^HIOM 

VO                 m  vo  m                00                iomcoio       Ov  co  Ov  Ov  <N  co 

WW                       M                             «    01    H                 M    HI    HI  M 

Course. 

N.  17  E. 

N.  8  E. 

N.  80  E. 
S.  82  E. 
N.  74  E. 

N.  70  E. 

N.  67  W. 

N.  19  E. 
N.  75  E. 
N.  80  E. 
S.  80  E. 

N.  88  E. 
S.  89  E. 
S.  86  E. 
N.  78  E. 
S.  76  E. 
N.  73  E. 

Wind. 

E. 

S.  E. 

N.  N.  W. 
E. 

E.  S.  E. 

W.  S.  W. 

S.  W. 

E.  S.  E. 
S.  b.  W. 
S.  W. 
N. 

S. 

s.  s.  w. 
w.  s.  w. 

N.  N.  E. 
N.  E. 
E. 

Temp. 

of 
Water. 

H  00  ^  co  w  Ov  OvoO  O  01  m  OvOO  r«  r»  to  f)  io  ■!)■  ti  O  M  <vi  w  O  O  OoOvO 
t*»vO  vo  vo  vO  iovO  \0       1>-  t^»vo  vOvOvOvOvOvOOvOvOvOvOvOvOvOvO  ioio 

Temp, 
of 
Air. 

O                 voOHIO                10                 O  vOt* 
*■«               lOt^vovo                vo                vo  1010 

Hour 
P.  M. 

S3        C3     c           d  c  

rr                       tJ-          OTfrO-5j-0<+          O       ■*  OOOOOO 

>>    2       2     2       >>2  2'^T^'0rC'« 

ci      S3          S3      fl          cj  $3  S3 

Hour 
A.  M. 

00  CI  CO   CI  00             00             00                       00             00         Ov  0 

Date. 

O  O   I    H   I    CM   I    co       I    1   10  1    1  vo   I   r^OO  Ov  O   I    h  N  to*  IOVO  f^OO 

i 

172 


Benjamin  Franklin 


[1785 


Therm.  Noon. 

Water. 

00  daooo  0 
*>»     t>»oo  r~» 

Air. 

r-  h  0  w  0  O  O 
*-oo  t^oo  00  00 

Variation 
of  the 
Needle. 

"0              0  O  O  to 

1/3 

<U  O 

>>   N                   O  *0   M  H 
|>    N                       <N    M    M  M 

Distance. 

.•O'toow'Oifla  t-<o  m  f)  f)  0  v>eo  \r>  10  0 

£  vO  t^vO  O  t^O  O  *  t^NH  -to  10  CO  CO  t^-vO  rj- 

Course. 

*****           •             fc>K;COto  ^ 

£               ^Wfe."    •    •      ^H**   •                  •    •  HC^ 
§  1  ^tO^^Hc^^^^H^^ 

^  co^co^cowyjyi^^yi^^^cfilz;^^!^ 

Winds. 

S  0 

S§          H    *                 .          h^.  ^ 

Therm.  P.  M. 

Water. 

OO    W    "♦  f/3rrt  O  CO          O    N    ^  lO  f"*.VO    r-»  OCO    O  00  rri 

io\0  «C  2  \0  *0  >0  r^f^t^-«^t^«--t^r^  r-00      ci>  t>- 

Air. 

tO  (S   O        S   O         H  00   H   CO  t^\0  *0  00   H   O  H   O  00 

vo  vo      vO          'O  r^vo  t—  r-  t»  r-«  i-»  r~»oo  t^oo  to  O  n 

Therm.  A.  M. 

Water. 

l^oo  00  n  "t  j>.vO  loco  O  M  to  to  ^t"  iovO  *0  oco  ooo  t>. 

Air. 

NNOto-*O^Or^OOMtOw  rro  O  *0  00  O  O  O  00 

■8 

0 

V>00  (OtoiO't-^-OOOwOMwOO  TfvO  o 

wiow'j-M'ttoMTr     ■^■tototo     to  w 

■<too  n  msijiH  to  io  r^co  w  to     10  io\o  t^oo 
m  m  m  m  «s  M  e)  w  M  tototocotototoco 

Latitude 
N. 

"lO00   0   0>OfO»ONOOl-lOr^<NlO^-t^  t^co 
MM                                   ^  't         tOtOMN-^-HtO  CO 

o 

000  MOrOHMO  lomcotOCOCOCO'<t  >O*0  *0 
^■^■^■^■"4-^rcocOcococococococococococo 

Dates. 

OO  h  m  «  t<)<t  iO<0  t^.00  O  O  w  <N  to      >ovO  t-~CO  O 

c-»  < 

f785l 


Essays 


i73 


Therm.  Noon. 

Water. 

1/*)  1/-)  q       ^vo  vO  00  CO  CO  CO  OOOwmmOw  OS  O  W 

r-~  t».eo  »g  t>.  t>.  t>.  r»  f»  t-»  t^oo  co  00  00  00  00  00  eo  **oo  *-» 

Air. 

f»  «^  O  S  10  O  O  MOO  OOO  O  CO  <0  *t  co  <N  00  00  i^OO  00 
«—  f^OO  0  *^00  00  00              *>.00  0Q00O0O00O  t^. 

Variation 
of  the 
Needle. 

O 

O 

o  vO 

eo 

j 

| 
i 

!t  «00  O  H  O  Tj-00  O  *t  "t  OsO  lO  ifr  «>e  IrtN  "too  vo 
VO  00       O  "t^O  M  CO*©  O  CO  Oi  00  W  M  CO  O>t>00  *>.  O  <N 

Course. 

.£    CO  £555 
^fc>'tO   •                         ..       .  {>' 

H«q               £  ^  CO  ^  H*-*«**H<*,fi  ,£>  ,Q           ^  H*£  j£ 

£co'co^co'^co'^co^^^^^^^P>^co'^t^£ 

Winds. 

w. 

W.  N.  W. 
W.  b.  S. 
N. 

W.  N.  W. 
W.  b.  N. 
S.  W.  b.  W. 
W. 

N.  N.  E. 
N.  E. 
E. 
E. 

S.  S.  W. 

s.  w. 

S.  W.  b.  s. 

s.  w.  \  w. 
s.  s.  w. 

N.  W.  b.  N. 
N.  W.  b.  N. 
N. 

N.  E. 
E.  N.  E. 

Therm.  P.  M. 

Water. 

O  NiO  Tf  \©  vO  O^CO  00  00  Ovrrj  OOOhOwOvcoO 

Air. 

N  O  00  in  a  O  w  cc  00  CO  w  S  co  co  co  N  O\00  tr>  r-  r-~ 
t^00        r-»  t-»O0  OO              t^OO  OCOOOOOOO  t^t^t^t^-t^ 

Therm.  A.  M. 

Water. 

VC 

■^•O  *>.  fOvO  vO  r--*0  CO  00  O-00  OOOOi-iOO(^ro 

Air. 

oo      ^  dm  o>     coo  r^oo  o  m  h  n)«  h  o  siniflN 

*§  . 
~* 

(OC<tSHM  +  toO«H^N«'tHOOOO«0 
M  *t  vo  CO  CO      W       io  ro      rfwo            tfl  h       ^  * 

OOoOOO  O  h  n  N  cO't  moo  HNVo«-~ONWMro  ttvO  00 
tOtOt^'*i,i-')-^f'<t,'}"*'fiinioui  uovo  \o  vO  vo  vO  vO 

Latitude 
N. 

oomowM  o  o  "t^n  loo  o  too  o  mo  o  w«o 

OH<}pl<)H't«5H«H         N   N  mommd  Ul^^N 
r^-VO   lA>lOli-)lOlOU-)TfTtT^-^Tj-Tl-LOVO  VOVO    *  "t  "1  ^ 

<OCOtyjco^COrOcocococococOcocO'OfOfOM5rOfOC'0 

Dates. 

O  m  s  f)<t  iovO  t^oo  Ov  O  w  h  «  to 't  *OVO  <>>0Q  Oi  O 
(MMNMNNMNWMCOCO  H 

g>  & 

<J  to 

i74  Benjamin  Franklin 


Observations 

July  31.  At  1  p.m.  the  Start  bore  W.  N.  W.  dis- 
tant six  leagues. 

August  1.  The  water  appears  luminous  in  the 
ship's  wake. 

—  2.  The  temperature  of  the  water  is  taken  at 
eight  in  the  morning  and  at  eight  in  the  evening. 

—  6.    The  water  appears  less  luminous. 

—  7.  Formegas  S.  W.  distant  32^-  degrees.  St. 
Mary's  S.  W.  %  S.  33  leagues. 

—  8.  From  this  date  the  temperature  of  the 
water  is  taken  at  eight  in  the  morning  and  at  six  in 
the  evening. 

—  10.  Moonlight,  which  prevents  the  luminous 
appearance  of  the  water. 

—  11.    A  strong  southerly  current. 

—  12.  Ditto.  From  this  date  the  temperature 
of  the  air  and  water  was  taken  at  noon,  as  well  as 
morning  and  evening. 

—  16.    Northerly  current. 

—  19.    First  saw  gulf  weed. 

—  21.    Southerly  current. 

—  22.    Again  saw  gulf  weed. 

—  24.  The  water  appeared  luminous  in  a  small 
degree  before  the  moon  rose. 

—  29.    No  moon,  yet  very  little  light  in  the  water. 

—  30.    Much  gulf  weed  to-day. 

—  31.  Ditto. 
September  1.  Ditto. 

—  2.    A  little  more  light  in  the  water. 

—  4.  No  gulf  weed  to-day  More  light  in  the 
water. 


17851 


Essays 


i75 


September  5.    Some  gulf  weed  again. 

—  6.  Little  light  in  the  water.  A  very  hard 
thunder-gust  in  the  night. 

—  7.    Little  gulf  weed. 

—  8.    More  light  in  the  water.    Little  gulf  weed. 

—  9.  Little  gulf  weed.  Little  light  in  the  water 
last  evening. 

—  10.  Saw  some  beds  of  rock-weed;  and  we 
were  surprised  to  observe  the  water  six  degrees 
colder  by  the  thermometer  than  the  preceding  noon. 

This  day  (10th)  the  thermometer  still  kept  de- 
scending, and  at  five  in  the  morning  of  the  nth  it 
was  in  water  as  low  as  70,  when  we  struck  soundings. 
The  same  evening  the  pilot  came  on  board,  and  we 
found  our  ship  about  five  degrees  of  longitude  ahead 
of  the  reckoning,  which  our  captain  accounted  for  by 
supposing  our  course  to  have  been  near  the  edge  of 
the  Gulf  Stream,  and  thus  an  eddy-current  always  in 
our  favor.  By  the  distance  we  ran  from  September 
9th,  in  the  evening,  till  we  struck  soundings,  we  must 
have  then  been  at  the  western  edge  of  the  Gulf 
Stream,  and  the  change  in  the  temperature  of  the 
water  was  probably  owing  to  our  suddenly  passing 
from  that  current  into  the  waters  of  our  own  climate. 

On  the  14th  of  August  the  following  experiment 
was  made.  The  weather  being  perfectly  calm,  an 
empty  bottle,  corked  very  tight,  was  sent  down 
twenty  fathoms,  and  it  was  drawn  up  still  empty. 
It  was  then  sent  down  again  thirty-five  fathoms, 
when  the  weight  of  the  water  having  forced  in  the 
cork,  it  was  drawn  up  full;  the  water  it  contained 
was  immediately  tried  by  the  thermometer,  and 


176  Benjamin  Franklin 


found  to  be  70,  which  was  six  degrees  colder  than  at 
the  surface.  The  lead  and  bottle  were  visible,  but 
not  very  distinctly  so,  at  the  depth  of  twelve  fathoms ; 
but,  when  only  seven  fathoms  deep,  they  were  per-  ] 
fectly  seen  from  the  ship.  This  experiment  was  thus 
repeated  September  nth,  when  we  were  in  sound- 
ings of  eighteen  fathoms.  A  keg  was  previously 
prepared  with  a  valve  at  each  end,  one  opening  in- 
ward, the  other  outward ;  this  was  sent  to  the  bottom 
in  expectation  that,  by  the  valves  being  both  open 
when  going  down,  and  both  shut  when  coming  up, 
it  would  keep  within  it  the  water  received  at  bottom. 
The  upper  valve  performed  its  office  well,  but  the 
under  one  did  not  shut  quite  close,  so  that  much  of 
the  water  was  lost  in  hauling  it  up  the  ship's  side. 
As  the  water,  in  the  keg's  passage  upwards,  could 
not  enter  at  the  top,  it  was  concluded  that  what 
water  remained  in  it  was  of  that  near  the  ground; 
and,  on  trying  this  by  the  thermometer,  it  was  found 
to  be  at  58,  which  was  12  degrees  colder  than  at  the 
surface. 

[This  last  Journal  was  obligingly  kept  for  me  by 
Mr.  J.  Williams,  my  fellow-passenger  in  the  London 
packet,  who  made  all  the  experiments  with  great 
exactness.] 


XXVI 


TO  JAMES  BOWDOIN 

READ  AT  A  MEETING  OF  THE  AMERICAN  PHILOSOPHICAL  SOCIETY,  JANU- 
ARY 15,  1790 

Philadelphia,  31  May,  1788. 

Dear  Sir: — I  received  your  favors  by  Messrs. 
Gore,  Hilliard,  and  Lee,  with  whose  conversation  I 
was  much  pleased,  and  wished  for  more  of  it;  but 
their  stay  with  us  was  too  short.  Whenever  you 
recommend  any  of  your  friends  to  me  you  oblige  me. 

I  want  to  know  whether  your  Philosophical  So- 
ciety 1  received  the  second  volume  of  our  Trans- 
actions. I  sent  it,  but  never  heard  of  its  arriving. 
If  it  miscarried  I  will  send  another.  Has  your 
Society  among  its  books  the  French  work  Sur  les 
Arts  et  les  Metiers?  It  is  voluminous,  well  executed, 
and  may  be  useful  in  our  country.  I  have  be- 
queathed it  them  in  my  will;  but  if  they  have  it 
already  I  will  substitute  something  else. 

Our  ancient  correspondence  used  to  have  some- 
thing philosophical  in  it.  As  you  are  now  more  free 
from  public  cares,  and  I  expect  to  be  so  in  a  few 

1  The  American  Academy  of  Arts  and  Sciences. 

177 


i78 


Benjamin  Franklin 


[1788 


months,  why  may  we  not  resume  that  kind  of  corre- 
spondence? Our  much  regretted  friend  Winthrop 
once  made  me  the  compliment  that  I  was  good  at 
starting  game  for  philosophers;  let  me  try  if  I  can 
start  a  little  for  you. 

Has  the  question,  How  came  the  earth  by  its  mag- 
netism? ever  been  considered? 

Is  it  likely  that  iron  ore  immediately  existed  when 
this  globe  was  first  formed;  or  may  it  not  rather  be 
supposed  a  gradual  production  of  time? 

If  the  earth  is  at  present  magnetical  in  virtue  of 
the  masses  of  iron  ore  contained  in  it,  might  not  some 
ages  pass  before  it  had  magnetic  polarity? 

Since  iron  ore  may  exist  without  that  polarity,  and 
by  being  placed  in  certain  circumstances  may  obtain 
it  from  an  external  cause,  is  it  not  possible  that  the 
earth  received  its  magnetism  from  some  such  cause? 

In  short,  may  not  a  magnetic  power  exist  through- 
out our  system,  perhaps  through  all  systems,  so  that 
if  men  could  make  a  voyage  in  the  starry  regions,  a 
compass  might  be  of  use?  And  may  not  such  uni- 
versal magnetism,  with  its  uniform  direction,  be  ser- 
viceable in  keeping  the  diurnal  revolution  of  a  planet 
more  steady  to  the  same  axis? 

Lastly,  as  the  poles  of  magnets  may  be  changed 
by  the  presence  of  stronger  magnets,  might  not,  in 
ancient  times,  the  near  passing  of  some  large  comet, 
of  greater  magnetic  power  than  this  globe  of  ours, 
have  been  a  means  of  changing  its  poles,  and  thereby 
wrecking  and  deranging  its  surface,  placing  in  differ- 
ent regions  the  effect  of  centrifugal  force,  so  as  to 


1788]  Essays  179 

raise  the  waters  of  the  sea  in  some,  while  they  were 
depressed  in  others? 

Let  me  add  another  question  or  two,  not  relating 
indeed  to  magnetism,  but,  however,  to  the  theory  of 
the  earth. 

Is  not  the  finding  of  great  quantities  of  shells  and 
bones  of  animals  (natural  to  hot  climates)  in  the  cold 
ones  of  our  present  world,  some  proof  that  its  poles 
have  been  changed  ?  Is  not  the  supposition,  that  the 
poles  have  been  changed,  the  easiest  way  of  account- 
ing for  the  deluge,  by  getting  rid  of  the  old  difficulty 
how  to  dispose  of  its  waters  after  it  was  over  ?  Since, 
if  the  poles  were  again  to  be  changed,  and  placed  in 
the  present  equator,  the  sea  would  fall  there  about 
fifteen  miles  in  height,  and  rise  as  much  in  the  pres- 
ent polar  regions;  and  the  effect  would  be  propor- 
tionable, if  the  new  poles  were  placed  anywhere 
between  the  present  and  the  equator. 

Does  not  the  apparent  wreck  of  the  surface  of  this 
globe,  thrown  up  into  long  ridges  of  mountains,  with 
strata  in  various  positions,  make  it  probable  that  its 
internal  mass  is  a  fluid;  but  a  fluid  so  dense  as  to 
float  the  heaviest  of  our  substances?  Do  we  know 
the  limit  of  condensation  air  is  capable  of?  Sup- 
posing it  to  grow  denser  within  the  surface,  in  the 
same  proportion  nearly  as  it  does  without,  at  what 
depth  may  it  be  equal  in  density  with  gold? 

Can  we  easily  conceive  how  the  strata  of  the  earth 
could  have  been  so  deranged,  if  it  had  not  been  a 
mere  shell  supported  by  a  heavier  fluid?  Would  not 
such  a  supposed  internal  fluid  globe  be  immediately 


180  Benjamin  Franklin  [1788 

sensible  of  a  change  in  the  situation  of  the  earth's 
axis,  alter  its  form,  and  thereby  burst  the  shell,  and 
throw  up  parts  of  it  above  the  rest?  As,  if  we 
would  alter  the  position  of  the  fluid  contained  in  the 
shell  of  an  egg,  and  place  its  longest  diameter  where 
the  shortest  now  is,  the  shell  must  break ;  but  would 
be  much  harder  to  break,  if  the  whole  internal  sub- 
stance were  as  solid  and  hard  as  the  shell. 

Might  not  a  wave,  by  any  means  raised  in  this  sup- 
posed internal  ocean  of  extremely  dense  fluid,  raise  in 
some  degree,  as  it  passes,  the  present  shell  of  incum- 
bent earth,  and  break  it  in  some  places,  as  in  earth- 
quakes? And  may  not  the  progress  of  such  wave, 
and  the  disorders  it  occasions  among  the  solids  of  the 
shell,  account  for  the  rumbling  sound  being  first 
heard  at  a  distance,  augmenting  as  it  approaches, 
and  gradually  dying  away  as  it  proceeds?  A  cir- 
cumstance observed  by  the  inhabitants  of  South 
America  in  their  last  great  earthquake;  that  noise 
coming  from  a  place  some  degrees  north  of  Lima, 
and  being  traced  by  inquiry  quite  down  to  Buenos 
Ayres,  proceeded  regularly  from  north  to  south  at 
the  rate  of   leagues  per  minute,  as  I  was  in- 
formed by  a  very  ingenious  Peruvian  whom  I  met 
with  at  Paris. 

B.  Franklin. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

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